If you are looking for hardware, Seagate already has an 80 Gb HD out and Directron.com has several adapters to refit an IDE drive to use SATA. (Just search for sata):
If you have a SATA drive:
Change your power supply molex connectors to SATA--
IDE to SATA Power Adapter, 4Pin IDE to 15Pin SATA $7.99
SATA cable--
Serial ATA Cable, 20", 7Pin Male to Male $7.99
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If you have an IDE drive:
SATA adapter, change IDE to SATA--
SOYO Serial ATA Cable & Riser Card $34.00
This package comes with 1 SATA cable and you need 2 of these riser cards, one for the drive and one for the motherboard if it does not have SATA build onto it.
There are also several SATA RAID controllers out, Promise and Adaptec are two that I am aware of.
I have an Adaptec developers kit and a Soyo riser card, but haven't had time to play with it yet. I will post some results when I get a chance.
Check out these links--
Promise Serial ATA Raid Controller
Adaptec Serial ATA Raid Controller
Directron.com
Seagate Serial ATA 80Gb Hard Drive