Mydesktop.utep.edu
You can access Mathematica (and other software) remotely from any computer. This should work for all operating systems. See http://admin.utep.edu/Default.aspx?tabid=65399 for more information.
Open your favorite browser (tested successfully with Windows 7 on Firefox 14 and IE 9; this did not work for me on GC 21, Safari 5, and Opera 12) and open mydesktop.utep.edu in a new tab.
1st time only: Your computer will ask you to download a plugin from Citrix:
After the download has finished, install the downloaded program:
Once installation is complete, you will see a login screen - use your UTEP credentials. (This is also where you start when you re-visit the web page.)
Go to the "Applications" tab:
Click on the Mathematica (or any other icon) - welcome to cloud computing!
Permit access a couple of times and close the Mathematica welcome screen. Go to File->Open and search for the file on your computer you want to work with.