I'm looking to upgrade my gfx card on my Dell Studio XPS 8100. I was wondering if I would be able to upgrade to a 550w power supply, with no problems, and what one you recommend (need good price). I would also like to know if the GeForce GTX 550 Ti would be compatible on my computer (fitment etc.).

Here is my current setup:

Dell Studio XPS 8100
Windows 7
Intel Core i5 CPU @ 3.3GHz
350w Power Supply
8GB RAM
GeForce 310 (1/2GB video ram)
DirectX 11


Please help, I want to have HD and high quality games now and in the future!