Is there a PC emulator for the iPad?

yes it names onlive desktop

Onlive Desktop is not a PC emulator, it is a remote screen app. You still need to run a PC to connect to it.

There is not enough power or memory in an ipad to run a PC emulator to allow it to run any current PC operating system, nor enough to play PC-based games. Try to look for the app-based version of the program you want to run on the PC. There are thousands of well-written apps that are optimized for the ipad.