Right-click My Computer -> Properties

Click on Remote tab

Check the box "Allow users to connect remotely to this computer"

Click Ok

Now find your IP, go to Start Menu -> Run

Type in "cmd" and hit OK

Type "ipconfig" and press enter

Write down your IP Address, you will need it at home

Start Menu -> Programs -> Accessories -> Remote Desktop Connection
(if you don't see it, it might be under Accessories -> Communications)

Enter your office PC's IP address in the "Computer" field.

Connect

*optional* if you want to put an icon on your desktop to connect directly, after you've entered the IP address, click "Options" and "Save As..." onto your desktop.