I would say when you booted without the 80 G drive installed, you automatically changed the order in the bios and made the larger drive the primary drive. The SATA connections seem to determine if a drive is Drive 0 or Drive 1, but the disk priority in the bios determines which drive is the primary, or at least that is the way it looks to me.
I am guessing that GRUB should be pointed at hd0,2 but the Win 7 partition does not appear to be active. Something to try, but I do not know if it will work, is to make the Win 7 partition active. Maybe it will boot to that partition. But once again, I do not know how GRUB works so don't do something that might mess up your boot.
I suppose the one thing is having an empty partition set to...