How can I tell if my graphics card is dying or if my drivers are incorrect?

I have a Sapphire Radeon 6870HD GPU. When I was doing some non-intensive stuff on my PC earlier today it crashed, and whenever it boots it:

• Goes through the windows spash screen
• Displays the 'welcome' with a bunch of horizontal artifacts
• Hangs at either a lightblue or just black screen. No error messages or BSODs

I have already tried switching to the onboard graphics, which had no such problem.

Now that I know something is wrong in the GPU department, how can I determine wether its' the drivers or the hardware?