If you need just a access for all machines from one place "Remote desktop connection " is enough. its available in both Xp & server 2003..
Start->programs->accessories->communications->remote desktop connections or type mstsc from run prompt..
you didn't type of requirement for project with client server environment .. if you need domain type instead of workgroup(workgroup is default type of connection available when computer are connected to network) then you have to ask some help with microsoft Professional people or you have to learn yourself(Microsoft's has plenty of documentation in its website )