I've tried WB3.1 with 1 meg...
it ran out of ram opening a window/folder?
you might get away with 1 meg if you just want to use it as a clock?
Read what I wrote a few posts back, ive ran it on 1 meg using ClassicWB lite no extras minimal install, WB 1.3 theme and 4 color mode, it runs fine, not optimal but fine.
Edit: I would still rather use an older WB version, but it will work.