OS : Windows 2008 R2
Turn off UAC temporarily. It will ease your pain along with setup and config.
Remember to Turn it back on afterwards.
Don’t Rush it!
Install WDS – reboot
Add PSP role in SCCM.
Remember to start as Admin to get the WSUS config.
If using WSUS Cert. You can add this to a GPO and off you Go.
Remember to start as Admin to get SQL connected.
Go 64bit if hardware is ready, check drivers, printers, and of course applications.
Remember to check Internet Explorer sites.
Remember Antivirus Exclusion! Or it will slow down your system and may malefunktion.
There is also a doc from Microsoft. Antivirus Exclusion Guidelines.