Just bought a C64 :-)

[Oliver]

If you want to make 303 type sounds, you will probably prefer the 8580 chip.  You may like to put two of them in your c64 as well.  It is possible to put an 8580 chip in a 6581 computer, but it takes a little more work.

You should also have a look at the midibox sid project at midibox.org (follow the micro C apps link), if you're interested in SID chip instruments.  It takes more work again, but it is capable of much more than the prophet64.  For 303ish sounds, you can have a look at the bassline mode.  You can also find info and links regarding the SID chip revisions.

[Oliver]

I think you will prefer the 8580.  If I remember correctly, the prophet64 bunch actually specify that an 8580 should be used.  I also think the bassline samples they provide, are made with 2 8580 chips, using a dual chip adapter board which they also designed.  You may be able to get such a board from them, but they don't provide the extra chip.

It seems you have come a long way from scoffing at electronica, huh?   :-D  Good stuff.  I look forward to seeing the music you produce.  Oh, also, you may like to know that music production, and home studio establishment can be very addictive.