AMD Athlon 64 X2 5000+ Brisbane 2.6GHz
BIOSTAR TFORCE TA790GX
CPU/MoBo Combo Deal = $140 w/ free shipping on the CPU
This combo is a very nice deal and the onboard HD3300 gfx will be more than enough.
OCZ SLI-Ready 2GB (2 x 1GB) DDR2 800
RAM = $20 (after MIR) w/ free shipping
Normally I wouldn't recommend RAM spec's at 2.1V, but for the price you can't argue. The similarly cheap
OCZ Gold 2GB (2 x 1GB) DDR2 800 is spec'd at 1.8V, but a guy in the comments said he only go it up to 4-5-5-12@2.1V.
Western Digital Caviar SE WD2500AAJS 250GB
HDD = $55 w/ free shipping
It's only $5 more expensive than the 160GB HDDs because of the free shipping. It's
really hard not to recommend the
WD6400AAKS because of it's superior speed and capacity per dollar, but if you're looking for the cheapest possible setup, the 250GB will due. Strongly consider splurging for the 640GB, though.
SAMSUNG 22X DVD±R SATA w/ LightScribe
DVD Burner = $26 w/ free shipping
Cheapest Lightscribe drive. It's only $2 more than the cheapest non-lightscribe drive.
OCZ StealthXStream OCZ600SXS
PSU = $55 (after MIR) w/ free shipping
600W is totally overkill for this build, but for only $55 it's hard to argue against it. And with the excess power, it'll leave the door open for a fairly beefy GPU upgrade in the future. You could save ~$20 and go with a smaller unit, but it'd be $20 well spent.
RAIDMAX APEX ATX-802B Black SECC Steel ATX Mid Tower
Case = $24 (after MIR) w/ free shipping
Top/Rear PSU mount, 120mm rear fan, mount for a 120mm front fan. Make sure you consider the shipping cost when picking out a cheap case.
Grand Total = $320 (plus $9 shipping on the MoBo)