9.10 to 10.04 BETA1 (Lucid) via CD

[Grizzly]

On 07 April 2010 at 11:49, Maxime Alarie 
Enlightened me with this:-RE: 9.10 to 10.04 BETA1 (Lucid) via

>Yes.

>Boot with the CD or if you can,  use a USB key, its much faster.  I think you can also
>use Synaptic, but you will probably need to have the cdrom in your repository. 

I booted fron a USB stick into 9.10
10.4 CD is in repository,  but I cant see a  way to do the upgrade (short of 
checking everything in Synaptic (after clearing all other repositories)

Sorry if I sound a real idiot