For the graphics card (I see you have the Sapphire 4870 Toxic listed) I can certainly say good choice, but make sure you get the 1GB version. Also, +1 at Azrael for the Corsair RAM (I've got some, it's simply excellent) and the Corsair PSU (got one of those too, and the HX620 is an excellent choice, and will run your system easily). I also have the Antec Three Hundred case, bear in mind you can't fill all of the hard drive bays with a 4870 graphics card as the power plugs go in the end, and so they have to sit ever so slightly in the hard drive bay to plug into the end. Also, if you can, get the Seagate Barracuda 7200.12 hard drive instead of the 7200.11, I believe the newer ones have 500GB platters (faster!).
@Azrael: Thanks for the advice on the Antec 300 being noisy As for the memory, would Corsair Dominator TWIN2X8500C5D 4096MB do nicely? @Pimonserry: Can't really change my harddrive, cause it is already lying on my desk and yes it is the 7200.11
That memory will do nicely, but unless you plan on overclocking you might not need RAM that high-grade.
