Edit 2: Fixed, use new release. (The one that doesn't begin with old.)
Edit: Due to a missed change, the browser may have some issues on some websites. Set general.useragent.compatMode.firefox to true in about:config to fix. This will be fixed in a new build in an hour or two.
Haven't tested on XP/Vista (extended kernel) nor have I stability tested.
Let me know what bugs or issues you encounter with it.