okay here is a little list I compiled. I live in the UK, so this list is from a local retailer. the price was about £406, so it should come to about $650 over there (US and canada seem to be cheaper for computers).
as for a case with a PSU, every single site will have some cheapo case. maybe go for an antec though - as far as I remember, they make decent cases and psus, so that solves the problem of bad quality psus.
Yes windows is kinda expensive. but dont buy the retail version, buy the oem version, its 1/3 of the price, and its the same thing.
256MB Asus 8500GT, Silent, PCI-E (x16), Mem 800 MHz, GPU 459 MHz, 16 Pipes, D-Sub/DVI-I/HDTV
Gigabyte GA M57SLI-S4 NF570 SLI, S AM2, PCI-E (x16), DDR2 400/533/667/800, SATA II, SATA RAID, ATX
AMD AM2 Athlon 64 3800+ Windsor Core, Dual Core 2GHz, 2x 512KB Cache, Energy Efficient Retail
2GB (2x1GB) CorsairTwinX XMS2, DDR2 PC2-6400 (800), 240 Pins, Non-ECC Unbuffered, CAS 5-5-5-12
160GB Samsung HD160HJ SpinPoint T166, SATA300, 7200 rpm, 8MB Cache, 8.9 ms, NCQ
Microsoft Windows Vista Home Premium 32Bit 1Pk OEM (DVD)
Antec NSK6500 uATX/ATX Super Mid Tower, has Hi-Efficiency 430W ATX12v v2.0 PSU
Optiarc (Sony/NEC) AD-7170S-0B 18x DVD±R, 8x DVD±DL, DVD+RW x8/-RW x6, DVD-RAM x12, SATA, Black, OEM