It may be possible to use specialized recovery tools which search for data signatures throughout the entire disk; one possible list of such tools might be How can I recover photo files from a CF memory card with a corrupt filesystem? on Photo.SE. The fact that the question as asked relates to CompactFlash memory cards makes little difference in terms of logical data recovery.
Your problem is much exacerbated because not only have you possibly repartitioned and certainly reformatted the drive (which probably wouldn't be so bad because it'd likely leave most of the file system structures intact, since they are placed in different locations on the disk and also have some degree of redundancy), but also copied loads of data onto it by installing Windows, data which can be placed at arbitrary locations. Recovering data from a formatted drive is non-trivial but doable; recovering data from a modern, overwritten drive is nigh impossible. Your situation with some areas of the drive overwritten sits somewhere in between those two.
A few references might be this 2007 OnTrack response about recovery of overwritten data, Wikipedia naming at least two 2006 sources saying one overwrite pass makes data unrecoverable, and ForensicsWiki referencing a 2008 paper with the purpose of settling the misconceptions around overwritten data recovery beliefs, which "has demonstrated that correctly wiped data cannot reasonably be retrieved even if it is of a small size or found only over small parts of the hard drive". The only real counterexample seems to be an article in Wired about data being recovered after being overwritten in the Bradley Manning case, but even if that was recovered from overwritten disk sectors (there are many other ways to gain access to such small pieces of data as are mentioned in the article) it still seems to only be a few specific files, not wholesale data recovery.
Frankly, in this case, I think you are out of luck. It might be possible to restore a few files here and there, but that will be about the extent of your success.
It may be worth your while to contact a few data recovery firms and ask whether they might be able to help. They might have access to specialized software which can do a better job at data recovery because you can explain what has happened to your disk, but it will be very expensive. Expect any such recovery efforts to cost four- to five-digit dollar amounts if you go that route, and of course there's still no guarantee of success.
Other than that, you'll probably have to think about what copies may be available from elsewhere: family members, uploaded to photo-sharing or social networking sites, etc etc.