re: Public network change to Private network
You can try to download the free Microsoft Virtual PC 2007 from here - http://www.microsoft.com/windows/vir...c/default.aspx and then install Vista on it or as many operating systems as you want. After that the Operating System can work in any network between themselves and thus can use the internet as well.
re: Public network change to Private network
Even I was facing same issue but was able to fix it, although this might not be what you are looking for, but you can give it a try. The network that I was using was showing as Unidentified Network in the Network and Sharing center and then I ran the Securty Policy Editor by going into Start and then Run and then typing secpol.msc. After that choose the Network List Policies under the Security Settings and then choose Unidentifed Network from the Network Names showing and then click on Action and then Properties and then set the location type to Private.