WinXP Pro - on the PC*. I had to go back to being dumb.
Windows Mobile 5 - on the HTC Apache 6700 (err..my phone)
Ubuntu 32bit - old laptop that won't turn on anymore.

Worked great once I got the ndis wrapper to properly handle the wireless card.
*Used to run Ubuntu x64 for a bit on the PC, but that was a massive headache trying to get NTFS support on x64 w/ a SATA RAID. Effectively, of 90gig internal storage, I could only really access 10gig.
note: I did manage to pull off NTFS read-only support for the SATA raid, but the write support for 64bit systems using a SATA Raid were non-existent at the time.
I've also attempted Debian (back in they day), Mandrake, when it was new, and RH, off and on.