You should be able to run squid (web proxy) on your server, with
http_access allow acl's for the external IP's of your work-sites (you wouldn't want everyone on the internet to access it), then simply route your browser through your home IP as its proxy, this way you can connect to any site on the internet bypassing all filtering. (Assuming you can connect to your home IP on one of these ports 80/8080/443/3128 etc.. squid will listen on whatever port you assign it)
Its free, and there is a windows version: http://squid.acmeconsulting.it/
Note: I haven't tested on windows 2008 or 64bit, but it does work on windows 2003/XP.
Failing that, you could setup a webserver that reflects the gmail site.. not sure if that would work though.. I bet you get IIS7 for free with 2008, so you could try something like this: http://www.iisproxy.net/download.html
You could also achieve it with SSH tunnelling.. There is a free OpenSSH windows version here: http://sourceforge.net/projects/sshwindows/files/OpenSSH%20for%20Windows%20-%20Release/
Read up here for a quick overview of SSH tunnelling: http://www.buzzsurf.com/surfatwork/