It's not really hard if you set up your "workstation" right. Do what I did- tape the sandpaper to a flat, sturdy surface. I used double sided tape, about a millimeter thick, so I had to line about 5 pieces of tape up to lay each piece of sandpaper on. A piece of glass will also work as a base for keeping sandpaper flat. If you have any old CPU's laying around, practice on them first. Also, you can find the grades of sandpaper needed in an automotive store or the automotive section of a place like Wal-Mart.
What Jakg said. Just unplug your PC and pop open the case. Unhook the power supply cables that go to the mobo and CPU, remove the little battery located on the board, wait about 10 minutes, put the battery back on, and plug everything back in.
Since I saw that Alien is wanting to base his system on a much higher end in another thread, I'd suggest going for an EVGA 780i, 2 9800GTX's (They scale in SLi MUCH better than 8 series cards) or a single card if SLi isn't wanted, a 700W+ PSU (SLI, 600 will do fine with no SLI), a Q9550 if you want a quad, and a WD Raptor to go along with the 500GB Seagate drive I suggested.
It was a while back in an LFSCAR race at Aston Club, driving an XRR. I had a pretty rubbish start, nailed the wall coming out of the chicane a few times. Got spun by another driver, had a hell of a time getting my car back onto the track, blew a tire around lap 45, and coming out of the final turn on the last lap, a tire gave out again and sent me into the sand, but luckily my car had enough momentum to make it through the kitty litter and made it to the line, finished 5th.
I should win an award for cramming the most crap into one sentence