Ubuntu 7.04 is great. You can use it as a LiveCD for testing, but that usually doesn't last long, as you'll want to install it. The LiveCD has a simple 5 click or so installer, and you can mount existing FAT-32 and NTFS partitions read/write by clicking their icon in the Computer place. When it's installed, you have to enter admin password to open a drive, or you can edit /etc/fstab (like any Linux distro) to mount drive at boot-up. You get Firefox, OpenOffice, video/audio players, Evolution email (which I never used), Gaim Instant Messenger, Synaptic Package Manager and apt-get commandline package manager, a bunch of games, some awesome 3d screensavers, and much more.