Need help choosing SSD

This is my first post here even though I frequent this site... I am hoping the community can help me out on this!

I have:

GA-X58A-UD3R motherboard
i7-920 CPU
HD 5850 graphics card
6GB DDR3 1333 ram

I built this computer myself and I'm not sure what other information is pertinent but I want to get rid of my 500GB HD or use it in tandem with a new SSD but I am not sure what to get. I want to get the best SSD possible given what I have. I only need around 250GB of space. Any help is appreciated!!

Thanks!
Jeff