Yep, and then some.
For accurate emulation+sound at least.
Much like the Amiga, the c64 isnt an easy machine to emulate.
MagiC64 can probably run (rough figure) %50-%60 of c64 software full speed/framerate with sound on a "fast" '060. Add another %15 for stuff that runs well, but with glitches.
So all up there's still some good c64 fun to be had on an amiga (Ive played some iO, Cabal, and some others on my 40 mhz '040 even), but there's going to be quite a bit of stuff that wont run well, or at all.
The emulators aiming for accuracy often recommend a 2ghz or thereabouts pc.