hmmm...
i would suggest, winlinux, installs on top of windows, you can unisntall it the control panel just liek any other windows application, no partitions
quite usefull if you dont get the hang of using linux, you can easily ininstall it less the hassles.
last time i checked doesnt work with xp.. around 150 MB more or less download (i think)
another distro i would suggest is ubuntu, free shipping, most hardware products are compatible, easy too install, (although i had problem uninstalling it, i forgot why,i thnk it was grub)
another woudl be SUSE.
basically, it depends on your needs/preferences. you can check out
http://distrowatch.com/ and also, iv posted somewhere here a guide/test on choosing what distro suits you.