I just installed Ubuntu (8.04), which I believe to basically be Debian with a nice interface.
There’s a neat utility called Wubi which handles the move from Windows to Ubuntu. It installs Ubuntu through Windows, handling partitioning, boot loader, and everything. It uses the Windows boot loader, adding Ubuntu as an option. It also shows up as an item in the “Uninstall Programs” menu, so you can get rid of it quickly — good if you’re just trying it out.
Right now I’m looking for a good virtual machine option. If I can dual boot into Windows from inside Ubuntu, I’m set! Any recommendations?