How to test my video memory on a 2010 13" MacBook Pro? I have MacBook Pro 13" Mid 2010, NVIDIA GeForce GT 320M

Recently (but right after installing OS X Lion) I've encountered artifacts on my screen. It's quite often and I can't say if the problem came from Lion (which brought me also problems with sleeping and few freezes, which I never had on Snow Leopard)

So is there any good way how to test my graphics card? or just it's video memory?
MBP 13" 2010 with NVidia GT320M uses shared video memory, so any ram test would be sufficient. My recommendation is to test using memtest86+. If there are problems - try removing one of the sims and run with half of your memory.