Have you tried updating the BIOS? Also, have you tried installing Windows 7 with the controller set to AUTO instead of AHCI?
Yesterday I was fiddling with a Zotac G43 ITX board and setting the controller to AHCI would cause the Windows 7 installer to lock up when detecting hardware. However, on AUTO Windows 7 installed just fine, and reported that Trim was working.
MBrown, what motherboard/chipset were you installing from?