Verified answer

every GPU is diferent, can't based it on just RAM alone. I currently have a Quadro FX that has 128mb, but out performs my friends Geforce 5600 GT (256mbp). Things you should compare when looking for a new GPU is

Bus Speed (most important)

RAM & RAM type (for instance, it might say 512 ram, but is running on 128ram TYPE, yeah, it's wierd)

PCI, PCI-E (8,16), AGP (old school), PCI-E2

BUT the one I'll recommend for anybody that is willing to pay for it would be

Quadro FX 5800 4GB - used for CGI's and professional stuff

important factors:

gpu clock speed

ram speed

ram bus (128 or 256-bit) don't bother with a 64-bit card under ANY circumstances. this also helps determine how much memory is useful and how much is overkill. 512mb is good for a 128-bit card and 1gb is good for a 256-bit card.

number of pixel pipes/stream processors (pretty much only useful when comparing 2 ATI or 2 nVidia cards)

type of games you play (shader-heavy ones will demand more pipes/stream processors and memory bandwidth-heavy ones need more memory bandwidth)

amount of RAM (easily the least important)

your monitors resolution also matters, but only in that a really low one may bottleneck the card, making a more powerful one a waste of $

always buy the best card you can afford. if you're a serious gamer you absolutely do NOT want to skimp here.

by the way, why do you need an upgrade? the 9800gt is still a powerful card and there isn't much that absolutely NEEDS something more. certainly I'd love to have one.

the two would be overkill on your res somewhat i don't see why waste money on a video automobile once you're taking part in at a res that small it somewhat is like figuring out to purchase a blu-ray participant to apply on a tube television from the 80s