Can I upgrade the video card after I purchase HP M9160F?

I am thinking about purchasing HP M9160F that has (NVIDIA GeForce 8600 GT 512MB installed) and I was just wondering if I can upgrade the video card later to GeForce 8800 GTX or GeForce 8800 GTS or GeForce 8800 GT, will this PC support SLI Technology? full specifications of the PC are: 1. Processor: Intel [...] http://bit.ly/nbs1fU