minimum hardware configurations for ubuntu

I am new to ubuntu 12.04 desktop/server versions. I would like to know minimum hardware requirements for

1. ubuntu 12.04 desktop versions
2. ubuntu 12.04 server version

I would like to use ubuntu for my project which involves the use of server running on JBoss, postgres which version of
ubuntu is good for a server machine. Is the desktop version enough? heard that using server version
requires good knowledge of commandline/shell.

I have a dell inspiron 1420 laptop with duel core intel processor. Can I load ubuntu 12.04 desktop/server in it.
Some one said that ubuntu will not load in some machine configurations?