Three ways. Firstly you could consider using a package such as Altiris, which takes images of PCs on your network. It can then be used to fix missing files as these can be backed up from the image, or to deploy new applications to the group of workstations once imaged.
Alternatively you can place exe's within the Netlogon directory. These programs are run at Login and so ALL users logging in will update their workstations with the new files.
This can be a bit problematic. You could alwaysconsider the Kixstart Login script tool as part of NT Resource kit. This will also give you a tool for scripting complex updates. (info available from technet.com)
Happy deploying