Think this might work:
MSI 760GM-E51 AM3 AMD 760G HDMI Micro ATX AMD Motherboard 70$
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130254
AMD Athlon II X2 240 Regor 2.8GHz 2 x 1MB L2 Cache Socket AM3 65W Dual-Core Processor 57$
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103688&cm_re=AMD_dual_core-_-19-103-688-_-Product
Crucial 3GB (3 x 1GB) 240-Pin DDR3 SDRAM DDR3 1333 Triple Channel Kit Desktop Memory 83$
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148245
Antec New Solution MicroATX Mid Tower Computer Case 380W Power 90$
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129035
Western Digital AV-GP WD10EVDS 1TB 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive 90$
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136496
Sony Optiarc Black 18X DVD-ROM 48X CD-ROM IDE DVD-ROM Drive Model 18$
http://www.newegg.com/Product/Product.aspx?Item=N82E16827131061&cm_re=DVD_drive-_-27-131-061-_-Product
Total= 408$ + S&H
If you wanted, you could swap out the motherboard for a DDR2 compatible one and maybe save a couple dollars.
The power supply should be enough, as that CPU only uses 65W. Oh, and the motherboard comes with integrated graphics + sound + 10/100/1000 mbs LAN. Not bad, I suppose. Well, hope this works for you (I can't believe I fit that terabyte drive in there- especially a WD).