I have a Netbook running Windows 7 and have been very pleased with it. Be aware though that this is a basic edition of Win 7 which doesn't have the fancy "eye candy" of its big brothers. There is also some limited functionality - it can join a Windows 7 "Homegroup" but cannot create one; it doesn't appear to allow its internet connection to be "shared".
However, in general it does just work as it should, unlike Vista which has been so problematical.
Be aware though that you will probably require a USB CD/DVD drive to be able to load software and possibly also to "recover" the operating syste should that ever become necessary.