Does you motherboard have on-board sound? It is very CPU intensive especially on older motherboards and could be the source of your problem. A soundblaster 5.1 is cheap and will make a huge difference. Also, take a closer look at your specs:
System barely covers the minimum spec for WinXP
Graphics card that is not fully DX8 compatible, never mind DX9.
I mean no offense as everyone has a budget, but please be realistic. Emulation is already processor intensive as it is, anyone who has disabled sound will have noticed how much extra speed they can get in certain situations. And with every game pushing the amiga to different limits regarding graphics and sound, there will always be some that struggle on slower machines. I am fortunate to have a fairly swift machine now (P4 2.4 gig), but my old P3 800 had a few problems with sound, especially Aladdin AGA. Just a few small upgrades (memory, graphics & sound) would make a big difference for not much cash.
I have never tried winfellow, and i don`t need to as WINUAE does everything i want.