What's the computer going to be used for? If it's a bit of everything, I'd go for this:
- CPU - Good enough for almost everything, if I hadn't been so stupid at the time, I would have got this or the E6600 over the Q6600.
- HDD, depends what you're going to store on it really but this should be good enough for most things plus it's a good brand.
- CPU cooler, very underrated, great performance for the money and quite good for overclocking.
- Disk drive. Can't really go wrong here.
- Memory. Always get a good brand here.
- PSU. NEVER get a piece of shit to supply the power 'cause it will probably end up blowing your PC up.
What video card you get really depends on what you want to do with the PC, but right now the best card for the money that will support DirectX10 games is the nVidia GeForce 8800GT 512MB which you can pick up for about £160.
BTW all that I've linked to which you could build a pretty good PC out of adds up to about £390 minus the graphics card.
If you don't know anything about building your own computer, it's quite simple really, here's a guide:
I did it and I'm a complete noob.