If these (possible) issues don't bother you or are less important than the possible performance gain, I'd suggest you give it a go. Obviously, I don't have to remind you to create an image of both your Mac OS X and Windows partition (see below) first, before you move ahead with changing the master boot record (MBR).

. Go to the key "HKEY_LOCAL_MACHINE_ System\CurrentControlSet\Services\msahci". Double-click on "Start" and change the value from whatever it is to "0". Repeat this step with the following keys (if present):

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStorV

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor

This will make Windows 7 look for the AHCI controller during the next boot! Restart your machine, hold down your option key and boot directly into Mac OS X Lion -- NOT into Windows!