upgrade from 10.04 to 10.10, wubi installed ubuntu

You can not AFAIK upgrade from the CD. But you can upgrade directly from Ubuntu if you have a decent internet connection. The procedure is the following:

1) Start the Update Manager (System 00> Administration)
2) Click Settings
3) In the "Release upgrade" field choose "Normal releases: from the drop down menu and then close
4) Press the "Check" button
5) if all is well you should get a " There is a newer version of Ubuntu available" messege in the top of the Update Manager window

You need the alternate ISO to upgrade to maverick. The desktop CD is not able to upgrade a current install.

using any upgrade in wubi will not touch your windows files at all. You should also have a backup of your important data so data corruption really shouldn't be a problem. Wubi is also a poor choice.

You can upgrade via the web using this:

sudo apt-get Install update-manager-core

gksudo gedit /etc/update-manager/release-upgrades
Change:
Prompt=lts
to:
Prompt=normal

Then run:
sudo do-release-upgrade

If the CD you have is the alternate ISO then you can mount the CD and run:

gksudo /media/cdrom0/cdromupgrade

and it will upgrade your OS using the CD offline.

Did you installed inside a Windows partition (Wubi) or side by side with Windows (on another partition) ?

Upgrading a wubi install to 10.10 is not recommended - known to fail when on the same partition as windows. There is also potential to overwrite drive MBR if not on same partition as windows.
(Actually, running recent grub-pc and grub-common updates on 10.04.1 is also known to fail with the same issues, so avoid these too)

The issues and fixes - if you've already done it - are detailed here: http://ubuntuforums.org/showthread.php?t=1639198

If you wish to upgrade, it's possible to backup your root.disk and your \ubuntu\winboot folder as well as the \wubildr file. Then you can just restore these to drop back to 10.04 if you have any issues. If you have other virtual disks (not including swap.disk) back these up too.