Looking to unify all my working environments

Hi,
Recently I've encountered a problem with trying to synchronize all of my working environments (2 Home Desktops [WinXP], 2 Laptops [WinXP + Ubuntu] and several research lab machines [Ubuntu + WinXP + WinVista]). I am often all over the place and getting working done on whatever machine is available at the time. Whether the work includes Java, C, C++ or web development, or just preparing talks and papers in Latex or other, it would be nice to sync things like my bookmarks, common applications (firefox, thunderbird) on the machines I work on. I am aware of several options that can accomplish this but would like some input before I commit to one or the other.
The several things I've heard of or even tried are:

• Online desktops
• iGoogle
• Compact OS on a USB key

It would be nice to know some examples of the above as well as new ideas.

Thanks!