Hello,
I am running lucid 10.04 (easypeasy) on an asus Eee Pc , kernel 2.6.32-41-generic-pae.
It's running really well except i am out of disk space so i attached an external usb H.D. and that works well too!

my question is: How can i make the external usb H.D. an extension of my operating system falling short of installing the O.S. there (since its running so well already) I would like to install and run software from the external usb H.D. would that be possible?

Appreciate the help.
Sixto

You would be better off upgrading your internal hdd/ssd and replacing it with a decent sized hdd. External storage is best used for backups and user data.

It is possible to merge the root file system and spread it between two or more storage devices but this not a good idea with removable storage as the system may fail to boot properly when the removable storage is not present.
If you have Wine installed, you can run some of the Portable AppsPortable Apps software from your external drive. (but not all will run well under Wine)
Some Java based apps also have stand-alone versions. (Sweethome3D for example)(Sweethome3D for example)
Generally, there is no simple 'plug&play' solution to what you're asking for.
Try experimenting with various software and see what you can accomplish.

Thank you very much qlue, will take your advice. and also do some more experimenting.

Sixto.