1.Right click your web application root folder, on the context menu, click "properties";
2.On the "web share" tab, "select share" folder, accept the deault settings to make your web application as a virtual direcotry;
3.Click startup => Run, type in "inetmgr", open the "internet information service";
4.Right click on the virtual directory you built just now under "Default website", select "properties";
5.On the "ASP.NET" tab, select "2.0.*****" for ASP.NET Version;
6.Open your web application project with vs.net 2005;
7.Right click the web application project (not solution), select "property pages";
8.Select "Start Options" in left tree;
9.In the server section, select "Use custom server", the "Base URL" will appear automatically, accept it;
10.Be sure to click "OK" to save the change.
Note: Cause I using a Simple Chinese version of Windows 2003 Server wirte down this step by step instruction, maybe some command names or tab names are not the same as your english version, but I think you can find these settiings esaily as a smart developer you are.