Thought some people might be interested, if you shop around you can get this model for around $250 USD. Quick specs:
Decent little amd cpu
4 sata ports on the backplane
1 internal sata port for 5th hdd/optical (has 5.25 slot for mounting)
1 internal usb port (yes, port, not header) handy for boot with a usb stick/ssd
comes with 2gb ddr3 ram (supports and a 250gb hdd
No windows tax
This would build a fantastic soho NAS (even more so once hdd prices drop again)