My G15 is the one thing I have had a problem with in Windows 7. If I leave the computer for hours, sometimes it loses contact with the computer. It still has power (lights are on) but the computer doesn't see it. Seems to be related to the USB connection. If I uninstall all the USB connections in Device Manager, then have the computer find new devices, it will refind the keyboard. Rebooting also works (but sometimes I don't want to do that).
Otherwise the keyboard works fine.
(I've been visting your site and these boards occasionally for awhile but never had anything to say.)