I thoroughly recommend Linux Mint 7 Main Edition which is built upon Ubuntu 9.04 Its easy to install and easy to use plus it comes with much of the software you are likely to need preinstalled
Linux Mint 7 Download
http://www.linuxmint.com/edition.php?id=38
Linux Mint 7 Release notes
http://www.linuxmint.com/rel_gloria_whatsnew.php
The Perfect Desktop - Linux Mint 7 (Gloria)
http://www.howtoforge.com/the-perfect-desktop-linux-mint-7-gloria
You download the ISO. image of Linux Mint 7 then you need to create a Bootable LiveCD for installation
Linux Mint 7 can also be run direct from the LiveCD from Booting up without touching your Hard Drive
ALSO WORTH CONSIDERING LINUX MINT 6
Linux Mint 6 Download
http://www.linuxmint.com/edition.php?id=31
Linux Mint 6 Release notes
http://www.linuxmint.com/rel_felicia_whatsnew.php
The Perfect Desktop - Linux Mint 6 (Felicia)
http://www.howtoforge.com/the-perfect-desktop-linux-mint-6-felicia
CURRENT SESSION
Linux Mint 7 ext4 (GRUB 2) with Compiz 0.8.2
http://www.linuxmint.com/edition.php?id=38
http://wiki.compiz-fusion.org/
LUg.