NAS, or Network Attached Storage is finally affordable to use at home. For a few weeks I have been running two $70 Coolmax CN-550 devices:

This is an external USB drive with an RJ-45 ethernet port. My devices both have 320GB hard discs and allowed me to dismantle a dedicate file server PC :) Now we only have one desktop PC in the house!!,
which is a far-cry from the five PC two years ago!! Simplicity means
more time for other hobbies, and this device has a very simple to use
web interface.

So what are the pros and cons of the CN-550 which right now is the pick of the affordable NAS:

Good:
Works seamlessly with final build of XMBC v1.0
Works seamlessly with Windows 2000, XP, and Vista
Can access files via a windows 'machine name', e.g. \MP3sRadiohead
Maintainable via a simple web interface
Simple to user Folder security (SMB username/ paswords)
Can easily become an FTP server
Stackable

Mild Annoyances:
XMBC 2.0 does not recognize these devices (yet)
Only uses IDE drives, not SATA
Discs must be formatted FAT32
Very slow for large data transfers over RJ45 (use USB 2.0 instead)
One of my 320GB Hard Discs does not work with power saving - I simply turned off sleep for that NAS device

Bad:
Reported not to work with some very large hard discs (750GB)