If you want to verify if .NET 2.0 is configured correctly on IIS or not then you could check following in IIS
Go to website properties>Home Directory>Configuration> Under application mapping verify that .aspx is mapped to "C:\WINNT\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll"
Then go to Web Service Extensions in IIS and see if Web Service Extension - ASP.NET v2.0.50727 is allowed or not. - It shd be allowed.
If both above are not present in IIS then go to command prompt and change directory to C:\WINNT\Microsoft.NET\Framework\v2.0.50727 and run
aspnet_regiis.exe -i
Above shd configure IIS for ASP.NET 2.0.
Then you could test a simple aspx page to see if it works.
For your ASPX page - What error do you see? Can you post complete error here.
HTH.
Cheers!
Ganesh