I can't sing enough praises about the wonderful, yet inexpensive system I just put together.
I went with the Shuttle MN31N motherboard - it's an nForce2 with the integrated GeForce4MX (with two VGA ports right on the board for two monitors) and the awesome SoundStorm audio. For well under a hundred US, it's tough to beat. I put a cheap, cheap, cheap AMD XP 2100+ in there and have just tried running it at higher speeds... without even trying hard, it's up to 2800+ and running smooth as silk!
If you're not a gamer, a single stick of 256MB DDR is maybe enough, but a second would be better. Two sticks of memory (dual channel) doubles the memory bandwidth and improves system perfomance a fair bit. Improves the onboard video by about double! (MX420 vs. MX440) if you do like the occasional 3D game every once and again.
In Canadian dollars, the board was ~$100, processor ~$100, 2x256MB DDR400 (very fast, Samsung) ~$100. Add a halfway decent case for $50 or so and you have a very nice system with more than acceptable audio and video too!
About $200-250US tops. Then add WinXP.
But I'll agree with some of these fellas... sometimes it's really hard to beat one of those awesome Dell packages if one comes up! If you scour the Hot Deals area here on Anandtech Forums (search for "Dell" once there) I'd seriously consider a cheap Dell 4600 system! You get a good machine and a warranty where someone *else* will take care of it for you. I'd advise against the 2400 systems if you even consider using your computer for more than just word processing and email.
But if you want to build your own, you could do really well with a setup like I mentioned above and gain some good experience while you're at it. It's frustrating sometimes, but very satisfying when it all comes together.
