I currently have an ATI Radeon X800-XT Platinum Edition. It worked awesome for the past few years, but now ive been having some trouble on my computer and assume i need a new card. For one, I cannot play 720p videos i download on my computer, as it makes the image jumpy and the audio sync goes out of whack. I have tried every possible codec for this, so I have to assume its my video card (I also have 3gigs ram and a brand new yummy audio card so it shouldnt be those i dont think).
Also, as far as i can tell, the damn thing in all its awesomeness has only Shader version 2.0, which means that newer pc games cant really be played on it.

Here is a link to the specs on the card itself:
ATI Radeon X800 XT Platinum Edition Specs. Graphics Cards Specifications.

Here are my current computer specs:
Windows XP
2.67 gigahertz Intel Pentium 4
ASUSTeK Computer INC. P4S800D-X Rev 1.xx Motherboard
3gb of system memory (it was very cheap 2 years ago, probably not the best)
Razer Barracuda AC-1 Gaming Audio Card

I am already in the process of building a new computer, so the question is, if I need to upgrade my graphics card, what card should i be looking into that will allow me to play newer pc games on pretty high settings, and if you dont think that the 720p video ability is due to my graphics card, what is??