Has anybody seen this blinking/artifact screen issue before?

No other way to describe it. You have to see for yourself.

This is a MacBookPro 4,1 17-inch Early 2008, 2.5GHz, 4GB, 250GB. Optical drive working fine, however it took a few boot attempts from a Drive Genius CD to get past the "corrupted scratches."

Not sure what instigates this issue, but am currently backing up the hard drive in Target Disk Mode, so there doesn't seem to be any issue with the HD. The computer will not boot to the desktop, even in Safe Mode. It always gets hung up on the boot screen with those corrupted scratches all over the screen. Clearly seems like it's a graphics card issue. I have not performed Apple Hardware Test yet as I'm without my original install discs.

Any advice? Experience with issues like this? I love fixing stuff on my own, but something tells me it might be time to begrudgingly pull out the credit card for repair or worse, a new computer. Thanks!