Looks like getting the timezone of the machine in Windows (and well, more usefully, the bias for local time translation) isn't as easy as I thought it would be. Sadly, Win32::Clock seems to have disappeared, so I've actually got to code it myself. How disappointing.
I've got to use Win32::API, and pack() nested structs for the parameter that GetTimeZoneInformation() takes. Considering I've never used pack() before for anything more than trivial, this should fun.
I'll get to that this evening, but for now I'm off to the Sunday Family Luncheon.