Testing graphics cards.

I was wondering if there is some way to test my graphics cards. I have 2 GeForce 9600Gt graphics cards running SLI. When I 1st set up my computer, which is custom built. Initially, I ran the Windows Experience rating tests. I was at 5.9 on all ratings. Which is the top rating. Recently I've updated my experience rating. It's only giving me a 5.7 on my graphics cards. I wondering how I can test these cards, and if I can see why my rating dropped. Also what can I do to bring my rating back up to 5.9.
Another question is, can me adjusting my resolution affect my rating?
I'm running WindowsVista 64bit.
Asus P5N-D mobo
8gb Patriot Viper series ram
Intel Core 2 Quad Q9650 processor
2 Sparkle GeForce 9600Gt Graphics w/ 2gb mem per card