my primary OS is Linux Mint, a derivative of Ubuntu part of the Debian Linux family. I also run windows 7 for programming assignments and games, though I'm trying to find ways around that.
Install virtualbox ose. It's in the ubuntu repos. It works fantastic. The idea of dual booting an OS is really inefficient and quite retarded once you think about it. However, running an OS inside an OS even for the simple tasks like you use windows 7 on occasion for is ideal.
I parted with windows a long time ago. I completed all of my college courses with linux. The only things i couldn't run in linux at the time with WINE was excel 2007 and photoshop. So i used a virtual machine program which was virtualbox ose and never registered my friends copy of xp and excel 2007 inside a virtual machine (re-install every 30 days, but with a virtual machine, this was a breeze). Once done with the software, i blasted the virtual machine out of existence (i really didn't feel like purchasing windows and excel 2007 which come at a premium for just one semester's use).
I use mepis pretty exclusively, but currently on linux mint while waiting for mepis 8.5 which is my holy grail. Mepis is a fantastic distribution! Great for computer diagnostics with the live cd. You can install it as the main OS too. Beginners take to it pretty fast, but is also great for intermediate and advanced users. It's base is debian stable running a newer stable kernel than what debian stable offers. Mepis also has it's own repository of backported software if you want the latest versions of several programs. The release mantra of mepis is to release when it's ready. Thank god they take their sweet ass time between releases, no rushed out the doors buggy **** from them compared to 6 month release cycle ****ers like fedora, ubuntu, and mandriva.
On the topic of mint, i keep it around for myself when i'm in a crunch and mainly for new users. Compared to ubuntu, there's a lot less to configure after install. After that, i switched my room mate over to it (it's what he gets for losing his xp cd key). He then switched his mom over to it because she had the same problem that he did eventually. I then switched my mom over to it on her two laptops which finally gets rid of that hacked version of xp that doesn't call home. New users to mint totally love the extra possibilities and the fact of no viruses and malware. People tend to be happy with linux if you have a good reason for them to switch as described above.