I've read many good things about intel-brand P4 boards. They have celeron options and some come with onboard sound, video, and LAN. Most intel boards are pretty stable with good enough performance. They make a DDR board (845?) that should work just fine, and it will probably only cost $50ish more than a similiar bargain board. I'd expect to make up the cost in time, not having to worry about VIA or SiS drivers, compatibility, etc etc.
YMMV of course, but I haven't heard anything bad about intel brand-name boards and they're typically quite trivial to install. My brother installed an intel i815 board in his own system a few years back and it was the first time I've ever seen a system install go that easily. Every single thing in that system worked right the first time.
Of course, the usual other considerations apply. Pick a good power supply and case, for example. Do some checking online to find a quiet hard drive since some drives are significantly noiser than others. That sort of thing can really make a difference when judging non-gaming system satisfaction. Not having to constantly fiddle with the system is worth much more than saving $20 or getting the last 5% of speed.
You might also consider the tiny P4 or AMD systems from Shuttle. They have one with an AGP slot that is quite slick. Tiny, lightweight, pretty quiet especially if you get a quiet hard drive, and plenty power for even light gaming. I'd personally get a P4 system to ensure a more stable heatsink mounting (safer if you expect the system to be moved occasionally) but they both have nearly identical features and decent performance. Plus with one AGP and one PCI slot, you can go with whatever level of video or sound performance you like and change it later too. Plus they look cool
