LogMeIn Compliment - Remote PC Access
We've used this software for various applications for some time now, but I've mentioned it to others and many still don't know of it. The standard version is absolutely free and allows you to control any PC anywhere with another by downloading the software on both and using password authorization. In fact, it isn't even limited to one on one and multiple computers can be access via each other.
In the past, we've gone the VPN route, but this is frankly, much simpler and easier to set up and use.
They do have premium versions that allow file passing and other advanced features, but it comes at a price that can be had with some open source software cheaper.
If all you need is to be able to access a desktop from a remote location, this company's download is a great tool, trustable, and you can't beat the price.