i don't Fold, so i don't know if its worth it or not to put an HD 4770 to work on F@H...perhaps some of our Folders can chime in w/ some opinions or statistics on how the HD 4770 compares to some other GPUs at F@H.
i don't know many other compatible projects off the top of my head. you already know about MW@H and Collatz, for which the HD 4770 would be very productive...perhaps PrimeGrid?
*EDIT* - without F@H first hand experience, and going strictly off of hearsay around the DC sub-forum, i'm going to guess that it'll be more worth your while to put the GPU on something other than F@H...not b/c you can earn more PPD w/ other proects than you would w/ F@H (after all, comparing the PPD of one project to that of another's is comparing apples to oranges), but rather b/c assigning the GPU to F@H could hurt your F@H production more than it helps it (CPUs are generally better than GPUs for F@H w/ respect to PPD, and GPUs can also consume a portion of the CPU that might otherwise be more productive were it devoted to F@H, and not the GPU).