060 or PPC

[pVC]

I'd say get 060 in any case. If you can afford and find, then get 060 with PPC. 040 just isn't quite enough for most of programs you will run, as most of them are 68k anyway. I'd recommend to get SCSI too, as it makes things much fluent on 68k systems.

64M will be fine for most of the things, but get 128M if you want to be sure 256M is viagra replacement

[pVC]

CPU usage will be something like 40% with 060 when playing MP3. You can do other stuff while listening music, but audio can cut sometimes if you do heavier stuff. You can affect to it by setting program priorities though... I'd still prefer some hw-decoder with 060. They won't use CPU for playing and 16bit is better than 14bit. Some sound cards have hw-decoding possibility and then there's some external hw-players.

Those fast IDE things have same problem than onboard IDE. They choke the CPU when transferring data. With SCSI the transfers are done with dma and there won't be any cpu load.

060 isn't quite enough for video streaming. You can watch low quality mpegs/avis, but on decent quality videos it's quite slideshow