It first screwed up a couple days ago when somewhere between being used by OS X and Windows XP the primary boot sector got corrupted, luckily the alternate boot sector was still there and fine so OS X repaired it with fdisk and all was well.
Now I went back and forth from OS X and Windows 7 which seems to have completely annihilated the drive. Before booting into Windows 7, I ran TestDisk in OS X. When I ran it in OS X, I saw a Mac HFS partition at the very beginning, and then it immediately skipped to 50% cylinders analysed and gave me three MS Data partitions. However, TestDisk only seemed able to recover that one Mac HFS partition and listed all the MS Data partitions as unrecoverable, so I left the disk be.
I was worried about stability as I had just installed 10.8, so I booted back into Windows 7 - Windows sees it as two big 1TB RAW partitions and OS X is still unable to repair the drive. OS X still sees it as one 2TB exFAT partition, but is unable to repair it or mount it.
So here are my screenshots of all the steps (don't mind the incomplete statuses of the scan, i've run it up to 100% before a few times and only got this far, was just redoing it for the screenshots):





from a deeper scan
I've been going through tons of threads in the Filesystem Repair and Partition Recovery boards, and I've seen other people with giant lists of Mac HFS partitions like this, but I'm not quite sure what to do with them.
The very first thing I did after zeroing out and formatting that drive as exFAT was to make a disk image of another hard drive which came out to be a little under 500GB. I assume that's at the beginning of my drive and is the data that I care about the most.