How can i Restrict Users From installing and uninstalling softwares

Dear

i have a domain windows 2000 server and clients some of windows xp and some of windows 2000
and now my problem is i want some users to stop installing and uninstalling softwares onto their system as if i gave them rights of local admin on to their systems then there is a problem for me
as they keep on install and uninstall is there
a way to stop them

thanks in advance