I've been using FS-UAE for a while, and it's been very useful. Before that I used WinUAE, which seems to have more features, but FS-UAE has everything I need, really. Can't tell you about performance, this machine is quite a power horse so it's all smooth to me. A problem that seems inherent with emulators is that there is a slight input/output lag. If it wasn't for that, I would probably only use emulators, but I'm getting more and more used to it.
