Thanks to theses forums & many others around the world, manufacturers have had to make their components overclocking 'friendly'

The gains to be had especially with chips like Intel's C2D are just ridiculous. Its now also foolproof, i.e. you'd either be a complete tool or unlucky to damage anything. All you have to do is pick-up the right parts (ones known to OC well) & you're good to go
Anyway, here's my spec suggestion...
Thrown in a new case & PSU because current hardware require good & efficient cooling & a nice stable ATX v2.
x PSU with 24-pin, PCI-E, SATA, etc connectors. Also for any modern GFX, minimum recommended on the +12V Rail is a combined 28A. Both should last you a long time & several more upgrades/builds.