If you are trying to install SCCM on Server 2008 SP1 and the SCCM install hangs take a look at the installation log. Most likely the last thing that you will see in the log is that the WAIK is being installed. Cancel the SCCM install and try to install the WAIK from downloaded iso media. If it hangs or you are presented with an error "installation failed" upgrade your Server 2008 SP1 to SP2 and try again. This worked for me ;-)