I have an old Dell D430 dual core processor that I have been beating around for the past 6 years. It is a "backup" to my Dell D630. It weighs in the 3#-5# range depending on which battery and charger I haul with it. I currently have it configured as a Linux machine with a 120gb SSD in it. It takes care of 95% of my needs in a compact computer. I have tried a couple of netbooks and have a Kindle Fire (company issued), but keep coming back to the old faithful Dell.
Aaron