I have 2 Lenovo netbooks (one convertible tablet, one regular netbook), one has been on constantly since I got it in 2009, the other has been on most of the time since I got it in 2010.
I'd avoid Acer, since they tend to build the RAM into the motherboard, so if it goes bad the whole system is screwed, and accessing the HDD is an annoying deal. But if all you want is one to work a year, pretty much any of them will do that (and they'll most likely have a 1yr warranty, anyway.)
Id stay 10in+, since a smaller keyboard is pretty hard to type on (and they start losing/annoyingly combining keys a lot more on 9 or 8 inch ones.)