captaincranky,
that makes sense, but i guess it sounds that PC3200 is the better memory. eh whatever, im happy with what i got.
jbright,
To get the latest BIOS, just go to Dell.com (open in IE browser as they require it for some strange reason) and under the "For Home" tab at the top left, click the "Support, Services, and Drivers option. Once you find your computer, you should find the update.
If this isn't the problem, then my only guess would be that the brand of your memory does not work properly. It's a stretch, but who knows. You never mentioned if you had either PC2700 or PC3200, but I know you mentioned it fit in, but which one did you buy? Also which brand is it? I used Crucial.
Another idea, maybe you don't have the memory firmly in. Make sure the tabs click in on the ends when you place the memory in.