here are the current cpu performance marks:
Tom's Hardware Guide Processors: CPU Charts
select by what your more likely to do you may also want to view the rig they tested on as this can cause discrepancies in the results.
Ram isn't great I would go with the g-skill Hz's if you can afford otherwise the G-skill value.
Are you going to overclock??
If not get a Asus p5b or Gigabyte ps3 if you are then the antec AW9D-max is a must have.,
The seagate 500gb run a little loud ive got 2 in raid 1 and theyre quite hot but very fast but 2x 320gb in a raid 1 setup would be more space and performance for about £10s more.
power supply is way too big for your requirements look at my specs in my signature and thats only 420w with much higher requirements