i don't think u need much... except a machine with MS Windows 2000 and above and knowledge in MS platform development.

actually the framework 2.0 has asp.net 2.0... u don't need VS.NET 2005, cause vs.net 2005 doesn't come cheap... alternatively u can try
Visual Web Developer Express http://msdn.microsoft.com/vstudio/express/vwd/

software and hardware requirement can be found here
http://msdn.microsoft.com/vstudio/express/vwd/download/

but if u have vs.net 2005 installed... you are ready to start development at any time