Okay so here is the system I built for you. Granted the price is a little bit more it totals $596.94 - $35.00 in rebates so $562.44 total after rebates.
$74.99 - $15.00 Rebate = $59.99. Better card also supports DX10 if you ever switch to Vista.
$99.99 - $20.00 Rebate = $79.99 Supports 1066FSB plus future support for 1333FSB. Also has 8 channel intergrated sound and decent overclocking potential.
G.SKill 2X1 gig ram
$114.99 2 gigs running in DDR2 low timings this ram is fast this is what I use. For full spec's check out my review on it in the review section.
I know its $160 over your budget but overall you'll be so much happier. You'll have a system that is really tunable, and more future proof.
$165.50 Most expensive part but much better than the CPU you have listed. Includes a heatsink/fan you could overclock to probally 2.6GHz roughly with this cpu/board/ram combo. More if you wanted aftermarket cooling.
Seagate Barracuda 250gb
$69.99 50 gigs more space then what you listed.
Samsung 18X DVD RW
$33.99 Should take care of all your burning needs. Didn't get a 2nd one don't see why you would need it. Order another one later when you get the money.
$38.99 I looked around and these are probally the best low end speakers.
A little more than you wanted to spend by $160 but a much better system that has more expandability and provides more tweaking.