If it says Microsoft HTTPAPI/2.0 then its someting to do with IIS or SQL Server
So go to Start -> Control Panel -> Programs and Features
Click the 'Turn windows features on and off' link in the left hand menu.
Wait for the list to load and then find 'Internet Information Services'
Un check the check boxes for the following items ( you may not see all of them )
1. IIS itself
2. Web Deploy 2.0
3. MS Sql Server Reporting service.
List of possible service names
http://blogs.technet.com/b/fort_sql/archive/2010/05/31/list-of-sql-server-service-names.aspx
Windows will then have a think for a while and then remove those applications, you will probably be asked to reboot to complete the uninstalls.
Reboot anyway when the uninstalls are complete.
Then try wamp again.