New computer questions

[commodore64]

Just bought a dell 2001fp. Was like a kid in a candy store waiting for it. It arrived today. Hooked up fine, but cannot get 1600x1200 resolution, because apparently my graphics card doesn't support it. Its the one that came on the motherboard when i bought the computer 4 years ago. Quickly went over to compusa and bought a new graphics card with 256mb memory?. The store clerk said it would work fine. Installed it and turned on the computer and the screen is blank, no picture. My friend thinks my motherboard won't support the new card.
So I called compaq support and they obviously weren't any help. But that's a whole different story.
Any suggestions on what I should buy for a new one. I obviously don't need a monitor or anything, just a new tower. Where should I look, what am I looking for to make sure I get that resolution? any help would be greatly appreciated. thanks