Which version of Ubuntu are you using? According to this article from 2008 Dell had ubuntu working on the 1525 back then. I'd recommend you either download the latest Dell version of Ubuntu or get 9.04 directly from Canonical.

 

To get Dells latest copy go here -> http://linux.dell.com/wiki/index.php/Ubuntu_9.04#Dell_OS_Factory_Recovery_9.04_DVD_ISO

To get Ubuntu 9.04 from Canonical go here -> http://www.ubuntu.com/

 

You might also want to check out this thread on Ubuntu Forums. I didn't read it all but it might help.

i got a ubuntu 9.04 cd from ubuntu. i run it on my 1525.it runs ok but no sound ,video. it asks for plugin from net, but i not able 2 make my broadband dialup as easy in windows.

pls help me b'cas ubuntu is my dream