The new Ubuntu comes out soon. 10.10, also known as Maverick Meerkat.
I am using Ubuntu 10.04, Lucid Lynx (with Long Term Support until April 2013), and am very happy with it. It works great on my desktop machines and on my Samsung netbook. Ubuntu 10.04 boots fast and leaves Windows 7 snoozing. Reports are that 10.00 boots even faster.
See the excellent review at ITworld if you want to see more.
Is it time you took the plunge?