If you have a Diamond Stealth X1550 that is already a powerful card, plus it has a 128BIT inferface. I think you could try out a 2400 HD Pro PCI card, i will do some serious testing tho with games.
Alright just want to say a few things:
About my PSU, 90watts
I have had this computer for over 5 years i believe, maybe 6. And my PSU still blows out very cool air. Room temps are very important, if the room is cool, my tower is cool. And i use 2 programs to keep an eye on how my GPU is. It pretty much stays at between 39c, to 44c, or 50c. I have use plenty of hardware and bought many stuff for this computer. This gateway computer was built with perfection and everything has been working just like i bought it from day one.
The items which i have install on this rig and use
I bought 2 sticks of ram, for a total of 512MB, one stick is dell (256 ) and the other one gateway (256mb )
Soundblaster Card, with EAX features.
I bought and use a Radeon 700064MB PCI card, a Radeon 9250 256MB PCI card, a FX5200 card, a FX5500 card, a BFG 6200 card, a Evga 6200 card and now i am u[/B]sing a 2400 HD Pro Radeon 256MB PCI card, which is the best. Neither one of those cards takes a strain on your computer, because all of those cards only needs 50 or 30watts.
I also upgraded from 20GB to 80GB WD Internal HD
I'm using a High Speed 2.0 Hub
500GB My book edtion external HD
As you can see i have use plenty of stuff on this computer, the 90watts PSU is made for this computer and really the things which i am using doesn't strain my computer like people think.
My PSU unit
I cant upgrade to a higher PSU because my tower is not small, but its not big either. I think i can only use 90's PSU's. I bought a second 90PSU, just in case the one i am using now dies on me, but that is not possible anytime soon
About using PCI slots
Well first things first, PCI cards are not the best obvious, but they do get the job done with certain stuff and games. I think PCI cards are amazing. Yea i could of bought a more powerful computer years ago, but i have been using this computer for years, no problems, so why get rid of it? PCI slots are for gaming, and even tho not AGP OR pci-e, they do get the job done to some degree
From Win9x to XP
This computer ship with windows98se, and on march 22 i finally did upgrade to XP. And not only is my computer faster, but everything is more smooth. And again, using xp doesn't take a strain on my computer at all really.
My last upgrade to this computer
I do plan on upgrading from 512MB to 1gb SOON
My Next big buy
Well this computer with the PCI slots is my first computer and i use it for everything. I do plan on buying a secondary computer tho, to enjoy the newer games , so everything is cool !