What's the model of the card? I assume most 040 cards will allow you to add at least 32MB RAM, possibly up to 128MB. Once you know the model, you can check it on the Big Book of Amiga Hardware and see what the maximum it supports is, then check out www.amigamaniac.com
And you know what would really enhance your Amiga experience even more? Either an Indivision AGA flicker fixer, so you can use Workbench and web applications at 1024 x 768, or a Mediator/Grex PCI board and a Radeon graphics card maybe. The graphics card is way more desirable if you're more into using your Amiga seriously, but the Indivision is essential if you want to play games on any modern display device (well, a few LCD TVs will sync down to the Amiga's output but composite won't look as good as VGA).