Of course I can't draw definitive conclusion from a couple of cases, but the 3 linux netbooks I've bought in 2007/2008 are still in use. And AFAIK my mother's 2008 aspire one only recently failed afer 4 years of heavy use.
My mom bought one for my sister this summer before her first year at university. An EeePC 10" something or other. I'm still using my 3-year-old Lenovo netbook as an Arduino programming machine because it's so portable and runs Linux.