If you have been updating incrementally, the sp1 will not do much more for you AFAIK. The only known expected change left for you would be the changes that were required by the DOJ because of MS manoeuvers to reduce competition.
If your system is working right and that you updated with the numerous security updates, I'd wait a while for the final verdict to come out. Why risk destroying your functioning system? "If it aint broken, don't fix it yet" is the advice I'd give right now.
--
Gilbert
