Which 11.04 File Do I Download?

Actually the one that says 64-bit PC (AMD64) desktop CD is the one you want "For a Desktop/Laptop".

If you want it for a server installation then go with the one that says 64-bit PC (AMD64) server install CD

64Bit Desktop -

64Bit Server -

64Bit Desktop (Torrent) -

64Bit Server (Torrent) -

You probably want this one:

Actually, the default UI for both 11.04 and 11.10 is unity. 11.04 was unity's debut release. Personally, while it was a little strange at first, I have come to love it. Very intuitive and attractive. With 11.10, they introduced a number of improvements such that I am really bummed that one of my laptops is stuck in 11.04 due to its video card support in 11.10 is lacking.

ubuntu-11.04-desktop-amd64.iso 64bit live cd [for fresh install] ubuntu-11.04-desktop-i386.iso 32bit live cd [for fresh install]

ubuntu-11.04-alternate-amd64.iso 64bit alternate cd [for upgrading from existing ubuntu] ubuntu-11.04-alternate-i386.iso 32bit alternate cd [for upgrading from existing ubuntu]

you have to download this ubuntu-11.04-desktop-amd64.iso