Here is how to make ASP debugging work:
1. Enable ASP debugging on the server. (IIS 5.1 right click on Virtual directory->properties->Configuration(in directory tab)->debugging tab->enable asp debugging)
2. Open classic ASP in VS 2005.
3. Set breakpoint.
4. View page in browser or run without debugging.
5. Debug | Attach to Process
6. Locate IIS ASP worker process (w3wp.exe on IIS6) which exposes x86 and Script and attach as Script.
When running on XP Pro/IIS 5, you need to attach to dllhost.exe instead of w3wp.exe. look for the one with Type "Script, x86" and the User Name column indicates your IIS process account (IWAM_machinename).