There are no emulators out there for PS3 yet. Even if there were, there aren't any desktop PCs powerful enough to emulate PS3, if you want to play a PS3 exclusive title, you'll just have to get that console. For PS2 there are some emulators out there, but they do require a very strong CPU for good performance. If you are running an old or cheap CPU, it's not going to work well, get yourself a PS2 in that case.