Can a netbook do these?

Unity 3D would be the only one I would question... If you buy the latest models you will probably be all right... I know Unity is not very friendly with older hardware. The others would be fine... I have an Acer Aspire One that is about 3 years old and runs Gimp, Stellarium, and Libreoffice without any problems at all in Ubuntu 10.04 netbook remix.