So for the longest time, well, about 5 months, I have used the mercurial package in cygwin as my mercurial at work where I run windows on my desktop. I use cygwin as my terminal on windows because it's unix like and window's command line is a piece of shit. No sane command/path completion nothing. Scripting is a nightmare etc. Anyway, the reason I used it was because I was under the false impression that all other mercurial installations wouldn't play nice with unixy paths.
Well, I was wrong. The hg.exe that is shipped with TortoiseHG deals with the paths, at least relative paths, nominally (Though, I'm sure something like cygwin's silly /cygdrive/c/file.txt wouldn't work). So I've been using cygwin's mercurial with TortioseHG's hgtk and kdiff3 for a couple months under the silly, wrong assumption that the hg.exe would junk my paths. oh well,
Uninstall the cygwin mercurial package and put TortoiseHG's path in my PATH environment variable (well it was already there) and everything's dandy. TortoiseHG just magically works on windows (though mercurial repos on the windows network are sloooooow). It's nice to be able to just type 'hg push' and have it work as well as "hg merge" the same way I do at home on my linux machine ("hg view" is "hgtk log" though).