You can upgrade to 10.10 now. But there are several reasons for it to fail.
You must be upgrading from 10.04 and not a previous version. You should
install all upgrades to 10.04, then launch the upgrade manager. Then if you
have lots of things installed from outside the repositories, it may not
upgrade which is what happened when I tried. In this case you will get an
error message, as I did.

Upgrades are always iffy. Some people have no problems while others just
won't be able to do it no matter how hard they try. You need to have all of
your ducks in a row and even then you cross your fingers. Besides a fresh
installation is better because you start with a clean slate.

It is also good to familiarise yourself with the new installer which has
been re-done in 10.10. I really like it. It allows you to check a box to
install restricted drivers and codecs. It allows you to download and install
updates (since the ISO was released). This starts to happen right away, even
before you add your user information. Finally it allows you to more easily
choose where to put Grub2. It was available before, but not easy to find.

While you are at it consider re-partitioning to create a separate /home
partition. This will save you much work in future re-installations. Once you
have done it then re-installing is as easy as upgrading. Basically you have
two separate mount points, / for root and /home for user. You will format /,
but not /home. just use the same user name every time and you are back in
business.

Something that you can do to make it easier it create a list of all
installed applications. You can do it from the command line using dpkg, but
you can also use the GUI. Open Synaptic package manager. Click on File in
the menu and Choose Save Markings as.. Give the file a name and check the
box Save Full State. Save it to a usb key. After re-installation. You can
then open this file in Synaptic (Read Markings in the File menu) and it will
re-install all of the packages. You just walk away and let Synaptic go to
work. You may have to install Synaptic in Maverick before you can do this as
Maverick uses Software Centre exclusively for package managing. You can do
it from the commandline with: sudo apt-get install synaptic or from the GUI
using Software Centre.

So with these two things in place, you never have to lose data as you can
just re-use your home folder (as long as it is on a separate partition and
you do NOT format it) and you can have Synaptic re-install everything that
is in the repositories that you previously have installed. It will not
re-install things outside the repositories. But there is even a way around
this. You can save your sources.lst to the usb key and then cut and paste
sections into your new sources.lst, replacing the version from lucid to
maverick with a text editor.

There is lots to learn in Linux, but almost everything can be changed. It is
a world of possibilities.