Help finding software for ASD.

Can someone help me in finding a software that will help us in distributing upgrades to our clients over the LAN. We spend so much time trying to keep up and it is not possible. I am not sure what kinds of software is out there to purchase. We arerunning an AS/400 for server and the clients use WinNT and 2000. We also may be using Linux soon for our stores. Can someone give me an idea on what to look for and some possible product names. Thanks