Can I control a Windows PC from my Macbook Pro?

I have a Macbook Pro running Mavericks, and a Windows PC running XP.

I don't use the Windows machine much, it's just for tasks using older software, etc. It's not connected to the network in the house because it runs XP which no longer receives security updates from MS.

What I would love to do is control the XP machine by using Remote Desktop from my Macbook, rather than having a separate keyboard, mouse and monitor connected to the XP machine.

I've no idea how to go about doing this if the XP machine isn't on the home network.

Any suggestions?