Ok i`ve wondered for a while how other people setup their system and perhaps if i go a bit over the top
Anyway this is how I do it:
1. Have a multiboot system - 1 OS[XP] for the DAW and the other`s for general purpose.
2. Use a tool called XPlite:
http://www.litepc.com/xplite.html
It lets you strip all the crap thats not needed for a DAW system.
3. Do some registry tweaks and disable all of the services thats not needed.
http://www.absdigital.co.uk/dloads/XPdawTweaks.htm.
4. Then do some defragging and system cleaning afterwards.