Windows setup does not support SATA on its own; you will have to press F6 when loading setup, and then provide the SATA drivers for your mobo's particular chipset using, thats right, a floppy disk. Ain't ancient technology wonderful?
The SATA drivers are problably on your mobo's installation CD somewhere. Just copy the driver folders (making sure to include the OEMSetup file) onto the floppy disk and insert the disk in your new computer when Windows setup prompts your for it.
It's a pain in the butt, but it's the only way you'll be able to install Windows on a SATA HDD.