08 Mac Pro display problem

Hello there, I have a 08 Mac Pro with a 2600 display card. (Sorry that can't remember the exact model no...) I was running it tonight and suddenly some checkers appears throughout my screen and I couldn't do anything. I was forced to power it off and on again. But after some seconds, the problem appears again and now, it appears even on the boot screen and remains unchanged. Attached is the screen. Is it the problem of the display card?? If I have to replace one, is it worth and ok to have 5770 right from that apple store for AE and FCPX? I'm waiting for the 2013 mac pro, so a bit hesitated to invest more on this Mac now like the 5870.... I'm still running snow leopard. Many many thanks!!!

Thanks for your idea. Sorry that I don't know how to flash it... Should I just buy a 6870, install it and then it'll work without boot screen? And then I just learn to 'flash' it to show the boot screen? Is is correct?? Many thanks!!

Thanks! I had a big problem in getting the standard 6 pin to mini 6 pin cable on the market today for the PC Card ... So I have ordered 5770 from apple online store. Hope it is really the card problem and can solve it right after I got the card. And I'm wondering will this card help in AE & FCP7 and X rendering? I mean the GPU. Thanks again!

I just don't know how to flash the card... I heard that GTX580/570 is good. Just couldn't find the cable here or I'll have to order it from the Internet. Probably take a while to reach my hand... And also don't know if the card just work right after installing on 10.6.8?? Even though without boot screen. Do I need to download driver or anything before installing? Obviously, my Mac is without any display card now and I can't see what it's doing when powering on... Sorry for my lack of knowledge on these issues...

You are right. I had a headache today in searching the cable... So just ordered 5770 directly from apple in the end. I don't have a second display with me unluckily.... Thanks for your advice.