I have had a Asus EeePC 1005HA for about 8 months.  I upgraded the ram to 2 gigs and am currently running windows xp on it.  It is definetly one of my better technology buys in the past year.  The 8 hr battery life is awesome.  I use this laptop for personal internet browsing / project management plugged into a 22 inch monitor when I am using it at a desk.  Mine runs a http, sql, and vnc server all the time as background tasks, with several firefox sessions, and one or 2 more applications going with no problem.  I dont consider it a desktop replacement as I have a file / media server for the big tasks.  

Pros - battery life, portability, power in small package, light, cost

Cons - small kb can be tedious, small screen can be annoying in a hurry on busy web pages, fingerprints on glossy black case