While I have equal access to a number of operating systems at home, I use
either my G4 or PowerBook G3 for Squeak.  For testing purposes, though, I
can run on:

1) MacOS9.1
2) MacOS9.2
3) MacOS9.2.1
4) MacOSX.1
5) Win98SE
6) WinCE3.0
7) Mandrake Linux 8.1
8) RedHat Linux 7.2
9) RedHat Linux 6.2
10) Apple ][ DOS 3.3 :)

-- Duane