Forgot username password

[Nigel Ridley]

I just bought a new Dell laptop with Ubuntu (I intend immediately to install kubuntu-desktop) and 
can't get into it :-( They didn't supply the username password and i have contacted my local Dell 
service center - but until they get back to me I figured that you guys could help me get into my 
new laptop.

How can I set a new [admin] username password?

Blessings,

Nigel