A problem with Windows 2000 Server and XP Client

We've been having this problem at work where we've started to introduce PCs with the XP pro operating system into our company. When each user logs on using the Microsft networks client they log onto a domain. I've been told that the settings on the server dictate what the user can do on locally. So the system is effectively part of the domain. Unfortunatelyl this user needs to add pieces of software to their system. To do this we had to give them administrator privileges. Once the software is installed we took away the administrator privileges. If the machine is restarted then the user can't load up the software that was installed. Does anyone know how to get round this problem?

Thanks.

iirc

it has to do with policies...
installing software though, there is something to set which allows installed software available to all users...but i can't remember where it is....