Besides ubuntu there are a good number of other small distros like Zenwalk, Knppix, Darnsmall, Puppy Linux, etc. that won't use much drive space if that is a small capcity drive like a 2, 3, 4, 6gb size drive. FreeDos, Solaris, OSX are a few orher types. The usual advice seen is to try a few live for cd versions of various distros in order to determine which is the most suitable for you. KDE or Gnome desktop is another consideration to add to that. Grub or Lilo boot loader.
Linux is open source and therefore sees various releases for each version. You can run some distro through a virtual machine in Windows to see which one you will go with. Some newer releases can now see MS types of programs/games run on them.