Monday, December 10, 2012 2:25 PM
Install it with DISM (run cmd.exe as admin), if the setup fails when you try to enable it under "add, remove features"
dism.exe /online /enable-feature /featurename:NetFX3 /Source:d:\sources\sxs /LimitAccess
Replace D: with your DVD drive/USB thumb drive or virtual ISO drive.