Personally I would download the eval cd of suse pro 9.2 which is free off the suse ftp server. it's about 3.1 gb though. The best way to choose a distro of linux is to use the various live cd which are available, they load into your ram and don't install onto your hard disk. See hich one you like best and download the full thing - which can be up to 5 cd's.
Personally I prefer KDE over gnome becuase it is more user friendly.
Don't try Gentoo for your first distro of linux as it has to be installed off a command line, which can be confusing if your not used to linux.