On XP machine, ensure that .NET framework is installed (whatever version that you want, e.g. .NET 2.0).
Once you have that you will need to register asp.net with IIS
To do that, go to C:\windows\microsoft.net\Framework\<go into folder with .net version> and Run
aspnet_regiis.exe -i
This will install asp.net extensions in IIS and then you can browse to aspx pages from IIS.
HTH.
~ Ganesh