I narrowed down my quest for a new gdu to these 2 options...but which is newer/better? They're both the same card, but different models by the same company...

(link to the items)
http://www.newegg.com/Product/Prod [...] gt&Ntk=all

Model #: 256-P2-N553-AX
or
Model #: 256-P2-N554-AX
???

also....this doesnt belong here but...
what type of memory should i buy to increase my internet cache? also, is there somethign to increase my overall computer performance?
One last thing...should i change from IE to FireFox??

Alright...the second model is the newer one...as far as which one is better, I couldn't tell you for sure. I'd bet on the newer revision as it likely fixed a minor "unofficial glitch" that the original models had.

Now for the performance issues. "Internet cache" is not an actual memory on the PC--the "cache" you may be referring to is most likely stored on the hard drive, so a faster hard drive may improve performance. As to FireFox versus IE? Nobody here wants to answer in fear of retaliation from fanboys I personally can't deal with the Firefox interface, and personally prefer the latest IE7 beta 3 (found here), but it is great for some people. Try firefox and if you like it, fine. If not, IE7 is much more secure than the current IE version.