Crikey. Snap crackle and pop, eh?
I'm not the most up to date guy on PC tech either but Intel's latest Sandy Bridge technology (now that a motherboard error that leaked too much current on one of the SATA ports is fixed) has to be the way to go. Make sure you buy the correct revision of motherboard if going Intel Sandy Bridge (I believe the issue ought to be mostly resolved now).
If I were you, I'd get myself over to Bit Tech and have a butchers at their monthly build your own PC feature. They split it into relevant categories depending on budget and what you want it for.
Bit Tech Buyers Guide for March 2011
Let us know if you need any further recommendations but do have a read at BT and go through their hardware configs. They have a useful forum too with a million tech heads at your disposal.
Good news is it's probably never been such a good time to buy in that hardware is way ahead of software so you'll be all right until um, Crysis 3 comes out! And Nvidia are back in the game and a more competitive option to AMD/ATI Radeon cards.
Lots of good hardware reviews at BT too - just skip to the conclusions like I do.