I really prefer NOT to run any variant of MS Windows if I can avoid it, but sometimes I can't. Here are the apps I like to install and run when I must use Windows. All programs listed here are available free. I've installed all these on my Dell Mini10 netbook running Windows 7 Premium Home Edition. Note PhotoStory3 must be installed in compatibility mode for older Windows platforms.
Miguel Guhlin has a much more extensive and helpful list of apps in his post, "Must Have Windows Software" from 10 January 2010.