choosing a PS is easy
Rule 1- You get what you pay for.
Rule2- figure what you are gonna do(OC, SLI, lots of fans or lights)
Rule3- are you gonna upgrade later(if yes modular is cool)
First go here and figure how much power you need
Than buy a GOOD PS like a Silverstone, FSP, PC Power And Cooling or Seasonic
I use a Silverstone Strider 400 ($50)and that has plenty of power for the X1800GTO.
Remember cheap PS make less than they advertise and good ones make MORE than they advertise.