MeOS is another free software package that GVOC has been using for the last year and we are pretty happy with it. Website is not yet available in English. Neither is there an English user guide... However, when you start up the program the first time, you can change the language in the GUI to English and there are nice help texts right in the user interface that describes most anything you need to do.
It supports individual races and relays, one-man relay, prologue/chase, score-O, etc, but it does not yet support multi-day events. You can pre-enter runners, classes and courses for big events, or just let runners download and build up the courses automatically for small events.
Runs on XP, Vista and Windows 7.
Direct download link:
http://www.melin.nu/meos/MeOSV25beta.exe