Hey Luke, made a similar move not too long ago. Simply because, in my estimation, both Pentax and Minolta had quit the game. Jumped to Nikon to avail myself of the luxury of being able to buy new manual focus prime lenses. Nikon appears to be "the last man standing" in that market. I've found nikon AIS lenses to be every bit as good as the favorites from Minolta and Pentax of old.
I have to add my endorsement for the Nikkor 28mm, f/2.8 AIS and the 105mm, f/2.5 AIS. Both are very simply outstanding - particularily the 28/2.8...this lens is nothing short of amazing. You owe it to yourself to at least shoot a couple of rolls with one.