SMS = Software management service... it's not cheap because of what it does. there are others like tivoli and altiris, but they are not cheap... Zenworks is a nortel product and then there are things from macrovision too... good luck...
I will be deploying an SMS 2003 site for our company in the coming months..I hope to have it done by the end of the year, but I know it will be very time consuming. Im very excited.