I've finally done it!

Office laptop running Hamachi and RealVNC
Originally uploaded by travelinlibrarian.

I've discovered Hamachi which allows you to set up completely secure VPNs and then, with RealVNC, I can have complete access to my home and office machines, from any other machine on my network. (More pics in flickr by clicking on the screenshot.) Untimately, what this allows me to do is securely use open WiFi hotspots without worry. You can read all about the software via the links and you can also listen to episode # 18 ("Hamachi" Rocks!) of the Security Now! podcast which explains it all. Oh, and it's all totally free. (No Mac version of Hamachi yet, but it's on the way.)