Okay, so you have the cabinet sitting in your bathroom between the bathtub and toilet. What's next?
Well, take account of what is already installed. For example, a regular cabinet will have a monitor, control panel and controls, a power supply, and the original arcade PCB. For the sake of simplicity, I will assume that the cabinet has a 25" monitor mounted horizontally in it. (Get a cabinet with a horizontally mounted monitor unless you want to set up a "speciality" cabinet for vertical games...).
Remove the power supply and PCB, and set them aside to store or sell. The monitor runs on a straight 110 (or 220 depending where you are) and the computer will use a computer power supply. So rip it out and forget about it for now.
Consider what you want on the control panel. Do you want a simple Street Fighter style panel, or one of those God-awful panels with 4 sticks, 30 buttons, 2 trackballs, a steering wheel, a flight yoke, 4 spinners and a cigar cutter? The Street Fighter layout is easier and with it you can play a majority of the games available on MAME. If you want a panel with everything on it, be prepared to custom make a panel for it and spend the rest of your natural born life trying to fit everything on there and getting it to work correctly. Also, a simple design will be more approachable for friends and guests who want to share in the glory of the cabinet with you. I suggest the Street Fighter layout (as if you hadn't guessed that already).
Is the cabinet rigged for stereo? If it is a "modern" cabinet, it probably is. But if you see only one speaker, it isn't. I wired the speakers of my cabinet directly to my Soundblaster card and it sounds great. If your cabinet is mono, it might be worth your while to make it stereo. Just use some 15$ USD speakers... they usually produce a good sound... and mount them in the marquee area. Don't forget to cut some holes (discreetly) so you can actually hear them.
Assuming that you looked at the monitor prior to the purchase, did it look weird, like bleeding colors, warped edges, etc? This may be due to a few things. The monitor may simply be out of adjustment, or it may need a "cap kit". When monitors grow old, the capacitors can "leak" and the diodes can become weak. First play with the display controls and see if that fixes the problem. If not, you might have to install a cap kit (or have one installed for you). Depending on who you have do it, it can cost anywhere from 30-100$ USD. The best bet is to call a video game distributor and look for people who do this sort of thing on the side. If you are bold enough to try it yourself, prepare for a lot of soldering.
Note: If you are unfamiliar with the way a monitor works, DON'T TOUCH IT AT ALL. The tube stores high voltage even after it has been without power for days. If you mess with it without knowing what you are doing, prepare to take the jolt of your life. While I have often been told that the shock can be fatal, I have not heard of an actual case of this happening... But I STILL don't take the chance and handle monitors with neurotic care. I once took a hit from a monitor I had "discharged" which caused me to drop the monitor and nearly wet myself. No joke, don't play around with a monitor!!
That being said, here is a (hopefully complete) list of the things you will need.
The cabinet w/ monitor
2 8-way joysticks (Wico is a good choice)
A computer (800 mhz or greater for the best results, higher if you have the cash)
10 gig HD or more
A soundcard (suggest Soundblaster 16 ISA, if your computer has ISA slots)
A decent videocard (one that is able to send a 15 khz signal to the arcade monitor... A 30 khz may damage the monitor. I use a Matrox G400, but I have heard that the Trident 3D is among the best)
Your choice of OS. I have no clue how Linux works, so I am using MSDOS 7.0 from my Win98 CD. It enables you to use the large capacity of the HD without actually going to Windows. IMHO, Windows sucks on a MAME cabinet. Use DOS.
A J-PAC from http://www.ultimarc.com...
It is a fingerboard that allows you to use the pre-existing JAMMA harness in the cabinet for the controls, as well as splits the 30 khz signal into 2 X 15 khz (so you can see the boot sequence and do command line stuff) as well as amplifies the signal to the monitor. This piece or hardware is worth every penny and I can't recommend it enough.
Wal-Mart sells a PC without Windows installed, and it has most of the stuff you would want in the cabinet-- a 800 MHZ processor, a decent hard drive. and a Trident video card for 199.99 USD. I might pick one up for my next cabinet.
So here is a quick price check (may not be entirely accurate)
Wal-Mart ubercomputer 199.99
16 pushbuttons ~15.00
2 joystick controllers ~28.00
Misc. wire, perhaps a spare JAMMA wiring harness just in case ~12.00
Misc. hardware, nuts and bolts ~5.00
Wood putty ~4.00
A cutting board ~6.00
Wire Nuts ~3.00
All prices are in USD
Tools you will need:
Screwdriver, both flathead and Philips
A drill with assorted drill bits
A wirecutter, wire stripper, or a set of snips
Soldering iron with solder
A "special" drill bit to cut holes in the panel for buttons and the joystick
A hammer (probably)
A pair of pliers (probably)
So, lets get started.
It is easiest to put the software on the hard drive by putting the hard drive in your computer and simply doing a drive-to-drive copy. I set my computer up and brought all of the software over the network... I probably won't do that again. By pulling the slave drive on your PC, switching the MAME cabinet's hard drive to slave, and doing a disk-to-disk copy is probably the best way to go... But I will leave that up to you.
Remove the mainboard and all of the other hardware from the case, including the power supply. Find something creative to do with the case. Use some spacers (I used the spacers that came attached to the arcade PCB) and mount the mainboard to the cutting board. I decided to use a cutting board so I could remove the mainboard and all other equipment from the cabinet if I ever decided to upgrade or do repairs. Mount the other hardware, such as the hard drive and the floppy drive to the cutting board as well.
Getting power to the cab is pretty straight foreward. Take the power cable you got with your Wal-Mart computer and chop it about eight inches from the end (where it plugs into the computer). Strip the wires and you should see a red, black, and green wire inside. Wire the monitor up directly to this line, and use the part you chopped off to plug into the power supply for the computer when you get it mounted.
Mount the COMPUTER power supply to the bottom of the cabinet, making sure that the wiring will reach wherever you decide to mount the cutting board in the cabinet. Plug the power connectors into the motherboard and the drives. Don't turn it on yet.
Take the keyboard extention cable and plug it into the PS2 connector in the motherboard, and connect the other end to the J-PAC. Plug the JAMMA connector to the J-PAC as well.
I am getting tired, I will continue this tomorrow, same thread...