I was thinking of upgrading my video card but i have a question?

I need to know if i can upgrade my video card to HD 5770. My computer currently has Intel core 2 duo processesor and a Nvidia Geforce G100 and upgrading it to a Ati Radeon HD 5770. I want to know if i am able to upgraded it or do i have to stick to Nvidia|||You should be fine. The Intel-Nvidia and AMD-ATI thing is only for SLI and Crossfire. (The intel mobos only support SLI and AMD only support Crossfire.)