There is no going back when you...
Unless you are hardcore into JRPGs and Fighting games. Though, PC may cure you of the former, especially if you never played the classics of PC RPGs, and future looks brighter for the latter on PC.
I highly recommend looking at games you are interested in and considering a 360 controller if they use it. Instant compatibility is just so, so worth it. Plus, it's hella comfy. Also, if you want to get into shmups and fighters but don't want to shell out $100+ for a quality arcade stick, I would highly recommend this:
http://www.pdp.com/p-1011-versus-controller-for-xbox-360.aspx
The thumb joystick thing takes a bit of getting used to, but since it is microswitches it is extremely precise once you have a feel for it. It is amazing. Xpadder is needed for a lot of games, but I think you can still get the old version for free (you don't need the new version for an all digital controller)