New Job, Windows and GTD

I am starting a new job in a week (woohoo!), it is a big step in every category except one: I will have to work on a Windows PC. I have become very comfortable on my Mac at work and home and have been using Actiontastic to organize myself (among many other failed experiments).

What options are there for cross platform GTD? I don't want to use a web-based app unless I can host it myself (a little nervous about down time and disappearing companies/services) and I want to be able to take my "home" project and use their contexts, etc. at work.

Any suggestions?