My rig is fairly standard, originally got it about a year ago now, however I have gradually stuck bits in it:
CPU:
Intel Core 2 Duo 6420 (2.13 Ghz, 4mb cache).
Low/mid end Core2, but it gives me a procesor score of 5.1 on vista so it's not too bad. In all honesty I doubt I strain it much, about the hardest thing I do with it is C&C 3.
Ram:
4x 1gb sticks, 667 mhz. This is a bit of a bad mix at the moment, I really need to replace the stock ram cards (2x 1gb) as they aren't nearly as good as the corsair Xms2 I put in later. Ah well.
HDD:
Some sort of 7,200 RPM 500 GB drive, I've never really been worried about it's spec's because I havent needed high preformance storage yet.
I plan to get another HDD soon, and begin running vista and my programs off that. I will probably go for either a 10,000 or 15,000 RPM drive. Most of my 500 GB is taken up by music and vid's so they hardly need a high speed drive.
Graphics:
XFX 8600 GT w/Zalman fan, 256 Gddr3 (lol.... whatever Gddr3 is.)
This thing runs slightly faster than the average 8600 GT, from what I understand it is a similar speed to an 8600 GTS. Seems to run my screen fine so I can't complain.
Sound:
Crap, Intergrated. Currently having a 2x 200 watt RMS amp built for me, however that will be a few months away. Once that's done I have a pair of Bower's and Wilkins DM 110's to use, theyvre awesome speakers (100 watts RMS, yeah the amp's overpowered).
Screen:
22" widescreen LCD. Always nice when playing RS as you can always do something and still have your RS window open. (5% of the time I have RS and a movie open

The rest is all stock dell, so the motherboard, dvd drive, case are all pretty booring/****.