I think a 266Mhz with 64MB Ram would just about cut the mustard aslong as you had a nice lightweight os on there like Win95 and had no other startup items!

I had a 100Mhz Toshiba with 48MB Ram which I installed Win95 onto, that played MP3s under 128kbps.

If You could pickup something with say a 500Mhz Processor, 128mb ram... you'd be laughing.