The main issue with the PSU is that stock ones included with cases are often lower quality, it's always better to go for a good brand such as Antec, PC Power & Cooling, Corsair, etc.
I'll cook you up a build and will edit the parts and prices in when I have something for you.
Few questions: Do you need an operating system? If so, what do you want?
Do you want a keyboard and mouse?
And do you want a monitor?
I'm assuming for now the answers are no as you've not included them in your build, but I'll try and have a build on standby which includes them all just in case.
Watch this space!
Edit: OK, here goes.
Antec 300 case - $54.95
GIGABYTE GA-EP45-UD3R motherboard - $119.95, $104.55 after rebate. Free 2Gb flash drive.
Intel Core 2 Duo E7300 CPU - $122.99.
G.Skill 2GB 800MHz RAM - $22.99.
MSI 9800GT 512MB OC - $119.99, $99.99 after rebate.
OCZ StealthXStream 500W PSU - $59.99, $29.99 after rebate.
Western Digital Caviar SE 500GB SATA HDD - $59.99.
LB Black DVDRW SATA drive - $23.99.
Total: $584.84 + shipping, $519.94 + shipping after rebate.
Remember that's excluding an OS, keyboard, mouse and display.
Fairly powerful system with lots of room for expansion. Could be worth adding another case fan for the front intake, something like
this for $8.99.
Let me know what you think.
Also, if anyone else has any suggestions, feel free to chime in.