I just got a new Dell Latitude E6320. 13" screen, i5-2520M, 8Gb Ram and a 128Gb SSD.
It is the first computer I have ever had that is completely silent. It is also the fastest machine I've ever had. Fan only comes on when doing something like encoding video - it's never come on when browsing the web / watching video.
They're quite expensive from the Dell site but I got mine from an eBay seller for much less. Build quality is superb (and yes it's a Dell)!
Another feature I love is that its very user serviceable - see here:http://support.dell.com/support/edocs/s ... index.html
Highly recommended if you can find one / afford it.