The American Alpine Institute points out a series of videos by Canadian climbing guide Mike Barter on the pre-equalization on anchors:
There is a little bit of controversy over pre-equalized anchors. Some feel that one leg of the anchor will get more force than another, which means that such an anchor could never be fully equalized. While there may be some truth to this concern, the impact on the anchor as a whole is minimal and professional climbing guides throughout the country are generally not concerned about it.
This may be basic stuff for many of you, but a quick refresher never hurts!