Windows 7 Starter Edition, the version loaded onto netbooks, isn't supposed to offer "advanced" features like ad-hoc network sharing. In this one case, however, finding this feature is as simple as typing the right phrase into the Start Menu search.
Rafael Rivera's Within Windows blog points out that while the dialog that normally starts the ad-hoc networking process in Windows 7 is disabled in Starter Edition, simply searching for adhoc allows you to start it up. That means being able to connect other computers, smartphones and Wi-Fi-enabled devices to your netbook when it's got a net connection. It's not quite as convenient as Virtual Wireless Networking, which you can enable with Connectify, but it does get the job done.
Windows 7 Starter hides but allows ad-hoc networking [Within Windows via PC World]