I haven't had particularly positive experiences with TortoiseGit myself. I really like the git model, but everything about it feels weird to me when I'm trying to use it on Windows. I often end up just using the cygwin version, but even that is far from perfect.
Honestly, for small projects that you want to opensource, I'd probably just host on google code and deal with SVN for the moment. It might be different if you were already a git expert, but I'm not sure that the learning curve is worth it for a small, windows-based project (esp. considering the # of windows developers who are likely to be turned off by it).
