I'm thinking of up grading my graphics card from a Ti4200 to a XFX GeForce 6600 GT and was wondering if this card will run on my system as my mobo only suports AGP x4
no it won't. many benchmarks show that a difference between 4x and 8x is surprisingly small. maybe 1-3 frames per second. now going from 8x to 2x is a different story...
Personally you'd probably be better off buying a new mobo that supported 8xAGP and then a decent graphics card. It'd probably cost you the same as putting in a high-end card into a 4xAGP box.