I'd go DOS on anything less than say a 550mHz, but at least Win98SE on anything faster. For a general use machine though, I'd never go back to Win98. XP is a much better OS.
For the record, the AWE32 and 64 do SB, SB Pro, and SB16 compatibility through emulation.
I'd suggest a SB16 PCI card instead as you don't need the MIDI stuff which the AWE's strong suit.