I've used both Remote Desktop and Teamviewer. Teamviewer is simpler than Remote Desktop. All you need to do is install the application on your home PC and leave it running. You don't even need to install it on your office PC. You can run it without installing. Good for people with no admin rights on office PCs. And the best part is that no need to forward any ports or anything. You just need the username and password that you setup on the home PC.

Remote desktop isn't too complicated. All you need to do is make sure it's enabled. Then, register with dyndns.org or no-ip.com for a dynamic domain name. They're free. You will need to install their client software on your PC. It doesn't matter that you're behind a router. The client software will automatically update the DDNS servers with the public IP that your router gets from the modem. Also, you would need to forward port 3389 on your router to the PC. It's preferable to have a static IP on the PC.