II7 is the default Internet information server for Window vista and window server 2008. In few cases I found that WCF and asp.net 2.0 is not working in iis7. This short of problem is often encountered, if you install dot net framework first and then install IIS7.
To resolve any kind of issue regarding this short of problems an easy way out is to reregister asp.net to IIS and register service model stuff to iis7.
To register asp.net go to your visual studio command prompt and type "aspnet_regiis -i" this will install and set all configuration to iis7. provided you have dot net 2.0 and later available in your machine. window vista by default have dot net 3.0.
To register wcf service to iis you got to run another tool called "ServiceModelReg.exe" this tool is located in "C:\WINDOWS\Microsoft.NET\Framework\v3.0\Windows Communication Foundation" directory. Provided that "c:" contains your windows directory. open the command prompt and go to the above mentioned directory with "cd" and run "ServiceModelReg.exe -i", that's it you are done.
A Special note
Same procedure can be used to resolve any issue in widows XP and windows server 2003. To work above things in windows vista you must run the command prompt with "run as administrator". For this right click on the command prompt and select run as administrator.Best of luck and Happy programming.