no, unfortunately K8 boards don't support Athlon XP's as they are socket 754; and the reason I included another sound card is that I have heard of Asus boards and people using their onboard sound. the people described it as "crackly" or "laggy"
I think Gigabyte boards have descent onboard sound, and most of them now have Nforce 2/3 chipsets
Zero Shift: yes a DVD burner can burn normal CD's, but not as fast as a standard CDR/RW drive
for the warranties: I am pretty sure most of the parts have waranties, but I did make sure that all the brands I included are among the more reputable for quality, so you shouldn't need to return them.
in about 1 year I have heard that AMD are only going to make 64-bit CPU's, I strongly reccomend the Athlon 64 as you should have it longer than an XP before you upgrade. after all, they said that 32-bit wasn't going to take off when it first came out.
if you don't want to go 64-bit then I would suggest This Gigabyte 7S748-L with Athlon XP 3200+ Barton