You just got it. Most softwares require local administrative rights. You can try adding them to the power users groups, but the reality is, in most cases, the administrators group is required.
Login as local administrator on a machine, go to start>settings>control panel>administrative tools>computer management.
Go to groups, open the administrators, from here, click the add button, and change the look in to the domain, give the domain admin name and password, and add the corresponding domain user account, or domain user groups that need local administrative rights to that computer.
Matt J.