We've been on the road for more than 18 months in Africa and South America, and updating our web site every 6 weeks or so. (Note that we cannot get around to update the site more often because of our writing style and the kind of photography we like - not because of the technicalities involved in actually uploading the files.)
We carry an Apple 12" iBook with a CR-RW drive but the process would be exactly the same with a Windows laptop:
1) We generate the web pages on the laptop. For that, use the tools you want (like FrontPage etc...)
2) Burn a CD with your web site and an FTP client such as the excellent FileZilla (http://filezilla.sourceforge.net/
3) Go to an internet cafe that lets you install applications on their machines (a very few don't). Note: do not ask for the permission to install the FTP client, just ask them for a machine with a CD drive and then go for it.
4) Launch the FTP client. Display the two file views by date - the files on the server and those on the CD - and upload only the pages that have been modified.
Enjoy your trip, don't spend too much time on the keyboard!
Pierre (& Merritt too)