Upgrading and saving your home partition is not a problem. Usually. :)
Backup just in case.

I ALWAYS do a clean installation and in since I began Ubuntu in 2006 I have
not lost any data. It is even easier if you are just upgrading. There is
always a first time, though, and according to Murphy's Law it will go wrong
at the worst possible time. So back up essential data if you can. That
would include your documents folder, picture folder, music folder, etc.
plus your virtual machines.

Then just do a normal distribution upgrade using your update manager.

www.omgubuntu.co.uk/.../ubuntu-10-04-12-04-upgrade-how-well-does-it-g\
o

Or try it from the terminal. :)

www.liberiangeek.net/.../upgrade-to-ubuntu-12-04-from-ubuntu-10-04-vi\
a-the-terminal/

If things go awry then you can still do a fresh installation and preserve
your home folder. You may need some help if it comes to that, but think
that it should go fine without resorting to it.