Author Miha Peternel could almost be regarded as the pioneer of C64 emulation - his emulator C64S was the first and for a long time was by far the best of what was available as well. I hear that C64S should still run on a 386, but certainly a 486 will do fine anyway. Another long-available C64 emulator, but sadly no longer supported by its original author, Wolfgang Lorenz. This emulator is very easy to use, with no keys on the keyboard being re-arranged i.e. pressing the apostrophe key will generate an apostrophe, no matter where the apostrophe key is on your PC's keyboard. It will also apparently run on a lowly 386.
Sound is sparse, but bearable most of the time.
This is a very nice emulator for Pentiums and above. One particularly handy feature about CCS64 is that it can run raw C64 programs with a .PRG extension as well as the standard .D64 disk image file-type. This is the one I'd recommend if your PC could handle it. I found this emulator very easy to use, better even than PC64, and in reality the only thing stopping this emulator from being my first choice is its compatiblity. It's high, but just not as high as CCS64.