Hi,
You want to install GNU/Linux, but don't have a cdrom/floppy/bootable usb drive? (I faced this challenge some time back and this document helped me http://marc.herbert.free.fr/linux/win2linstall.html ). It is easier now. You can install Debian GNU/Linux if you have a working internet connection and you are running a Microsoft Windows Operating system. Debian now has an installer that runs on Windows!!!
http://goodbye-microsoft.com.nyud.net:8090/
(the site seems to be suffering from high requests at the moment. So other pages might not work)
Cheers Praveen