What is the purpose of not offering SP1 to users based on which device drivers they have?
We are doing this in order to help provide our customers the best update experience we can by using Windows Update to selectively offer SP1 to PCs. In cases where a PC has one or more of the drivers that we believe may be problematic, Windows Update will not offer SP1. (You can see a complete list of situations where SP1 won’t install and specific problematic drivers here). As new drivers that address these issues are made available, we are using Windows Update to also deliver updated drivers to PCs. Once the updated drivers are delivered and replace the potentially problematic driver on a PC, SP1 will then be offered to that PC.