Commodore C64 emulation in Linux is bad so far, just like Nintendo 64 is... oh, and Sega too (Gens works just like the Windows version, but quite choppy).
is probably the best one. There's also EC64, which is faster then Vice.
But I warn you though... those emulators are quite choppy for Linux, it's not nearly as good as Hoxs64 or CCS64 for Windows/DOS.
But give it a shot, you may like it anyway
. I'm a big fan of emulators and I still am waiting to see quality emulators in Linux like zsnes (if you can compile it...) and ePSXe...