Group ploicy doesnt get applied to users on my network how to solve this ?

I have a win2003 server and 25 workstations, I just created new OU and placed a new usesr in it and added a new GPO for this OU( not deafult domain policy) and applied some security for this OU . I i logged on my workstaion using this user which is in OU, But the policy seems doesnt change . I tired the policy of disabiling the controlpanel for this user, it dint apply for the workstation but when i logged on to my server using this user id , i saw its got applyed there on the server, that means the polcy of this user getting applied on the serever but not on my workstation. pls just help me.Its really something important for me.

If its worth saying this, My workstations are WinXP.