Hi Kris,
This seems related to the questions we've seen on monitoring a Windows service:
Here are a few related posts. I think the best practice solution would be to write a web page which checks the status of the service on the local server and then responds with a specific string indicating success or failure. You could then configure an HTTP monitor which polls that web page.
Monitoring a windows service
http://devcentral.f5.com/Default.aspx?tabid=53&forumid=32&tpage=1&view=topic&postid=23312
Monitoring a Microsoft Windows Service
http://devcentral.f5.com/Default.aspx?tabid=53&forumid=32&tpage=1&view=topic&postid=32382
I don't know of any Linux utilities that could be used to remotely access a Windows host and get or set registry keys. I supposed you could install an SSH server on the Windows hosts; create a script that establishes an SSH connection and runs the regedit commands to check for specific key(s); and then use that script as an external monitor for LTM. All in all, it seems fairly complicated.
Aaron