For parts... No 1, don't skimp on the PSU. No 2, don't believe the numbers on the PSU. No 3, don't buy a PSU that doesn't have a decent length of parts and labour warranty.
OK, the general drift is that PSUs are awful things, in case I wasn't clear
I wish I had something to recommend, but I've seen quite a few expensive ones blow up as well as lots of the cheap and horrible ones.
Other than that... some hints as to what your main usage is would be good.
Whatever, buy a decent amount of RAM (>2Gb, if you're going to use the machine lots) because it's very cheap.
Graphics cards - by the sound of it you do something graphics related and so my recommendation is something Nvidia; avoid the cheaper GS models that use system RAM to top up their own (whether you like it or not).
Disks... buy two, they're horrible unreliable things too - a RAID 1 array (mirrored) is not a replacement for backups but can save you a lot of hassle if a disk dies on you at a bad moment (which they always do.)
These days, the CPU isn't such an important consideration as it once was. Any of the dual-core AMD or Intel processors will give you very good performance.
Can't really say more without having a good idea of the intended usage, though you're probably fed up of the sound of my voice by now anyway