Toad,
Good choices all around (but dunno about your soundcard choice...just no experience with it on my part).
Still, is money a real object here? If not, then for an extra $136, I would suggest a couple of changes to your list (all prices are from newegg):
Athlon XP 2100 OEM ($188)
OCZ technology 256MB PC2700 memory. It's CL 2 and has some excellent timings. ($77)
GF4 TI4400 instead of the 4200. ($229)
While these guys are correct that 333Mhz DDR isn't "tweaked out" yet, real world tests do show a decent increase in performance over PC2100. Still, if you are dead set on PC2100, don't buy cheap, generic stuff. Spend a little more and get good memory....it is well worth the minor investment.
As for heatsinks, it is worth an extra $25 for a good sink and fan. Research HSF's on the net and get an idea of just how effective a good one is versus the stock units. Although the stock unit is adequate and your CPU may not die in the course of the 3 year warranty, you might experience glitches or lockups related to heat....and that can be a royal beotch to diagnose (usually you start thinking bad video drivers, sound, etc and 2 weeks of hair pulling and windows reloading later, someone says "dude, it's too hot"...and, well you get the idea).
Right now I am anxiously awaiting my goodies box from newegg. I ordered the Soyo Dragon Ultra mobo, Athlon XP 2100, two 512MB sticks of OCZ tech PC2700 (CL 2), 7200 RPM Maxtor 40GB ATA133 HDD with fluid bearing, a set of shielded, round IDE and floppy cables. I've also got an Arkua 7228 heatsink (a licensed copy of the Thermosonic Thermoengine with mods) and a tube of Arctic Silver 3 coming from The Heatsink Factory. I also ordered a 120mm-60mm machined aluminum fan adapter and an Enermax 120mm fan (108 CFM baby!)....yes, I plan to overclock ;-)
I already have the GF4 TI4600 that I got the other day.
The Arkua heatsink and stock fan costs $24.99 and is rated as one of the top coolers around. It holds its own against expensive heatsinks such as the monster sized Alpha PAL and Swiftechs new MCX462 (which costs $55 for the heatsink alone!).
Even if you don't plan to overclock, a good heatsink and fan is well worth the little money it costs.