Teamviewer - install on host, or XP VM as well?

I've built a PC for the gliding club to run their accounts software.  It's W7x64 Pro, and runs the old accounts in an XP VM.

I want to be able to get at either machine for support purposes and plan to use TeamViewer.  Should I install it just in the host, or in both?  In other words, if I install it on the host will that give me access to the VM?