To begin with I would immediately forget Ubuntu 10.04 and Linux Mint 9 as there are multiple stability issues with both releases. With Linux Mint 9 this is not surprising seeing as it is built upon Ubuntu 10.04 so therefore inherits many of the BUGS
I started out with Linux in 2006 with Ubuntu 6.10 whilst Dual Booting with XP. In 2007 I converted entirely to Linux with Linux Mint 3.1 which was based upon Ubuntu 7.04 which in itself was a fine release.
I have worked with all the Ubuntu and Linux Mint releases at one time or another and have become settled with Linux Mint 7 and Linux Mint 8
Linux Mint 7 Download
http://www.linuxmint.com/edition.php?id=38
The Perfect Desktop - Linux Mint 7 (Gloria)
http://www.howtoforge.com/the-perfect-desktop-linux-mint-7-gloria
Linux Mint 8 Download
http://www.linuxmint.com/edition.php?id=44
The Perfect Desktop - Linux Mint 8 (Helena)
http://www.howtoforge.com/the-perfect-desktop-linux-mint-8-helena
Modern Linux Mint is actually very different in some respects even though Ubuntu is at its base. True there was a time when Linux Mint was no more than Ubuntu with facepaint and a few extra repositories to make it so it could run 'out of the box' without the need to install Flash player, codecs. etc.
Linux Mint has now matured in to a fully fledged ready to go alternative to proprietary platforms with many people rather waiting the new release of Linux Mint and not installing the latest Ubuntu and opting to perhaps run it from the LiveCD
Furthermore Linux Mint is ready to break its ties to Ubuntu and go Debian therefore making for an even more stable distro. this would be advantagous given how poor Linux Mint 9 is on the back of Ubuntu 10.04
Debian (origin of Ubuntu) has much in common most importantly Package Management
http://www.debian.org/
LUg.