I asked my friend for a list of specs for a new computer and he gave me this.
Intel i5 760 2.8 ghz
4G Kit ddr3 G.Skill-Ripjaws 1333
Nvidia GeForce GTX 460
Hitachi (Japanese Brand) SATA 500G
I asked if everything was compatible and he said maybe so I got worried that I would be wasting money so I ask will the system work?
That will work, but I'm not sure that the PSU is going to be a very good one. You only probably need a 500watt one for starters, try and get a better brand (Antec, Corsair, OCZ, Coolermaster, XFX......) The rest of that stuff is compatible. Dont forget your optical drive!! Not expensive. $20 or so, maybe £12-15/euros......
With a $15 difference between a 500 GB and 1000 GB drive, I'd invest in the larger. Brand not really significant, pick the one that best fits your apps, but avoid lemons like the 7200.11 (7200.12 is fine, the 11's had a firmware issue)