I have a friend who upgraded his PC to a Gigabyte 7NN8X and an AMD Athlon XP 2500; its onboard sound was far from glitchy, and it turned out really fast, also it has Dual BIOS so if you fry one, you've got a backup to roll back on. IMO this board is very good, and really easy to overclock on, but if you want to go with ASUS, that's fine.
for the price of SATA drives, get either a 120 or 160GB drive; the 120GB is only a few bux more than the 80 so is prolly best for price:space ratio
Also, either go with Seagate or Western Digital; I would go with Seagate for being the quietest ever 7200RPM Hard Drives and also very good quality.
for RAM I would go with Corsair Micro or Kingston - but preferrably Corsair because they usually come with their own cooling, and are prolly compatible with more boards.
if you're gonna get video card, Radeon 9600 Pro/XT is the one to get for price verses performance
the XT's overclock themselves for higher demand, and underclock themselves when overheating.