remote cpmputer access

i have 3 computers at work that i want to set up on a remote access thing
one computer is the admin and the 2 oterhs i want to set up are public computers
the idea is that the admin can remotely use the computers that are in the next room over without going in there… that way he can check up on what the peple using the computers are doing… i have seen this done
all the computers are win xp
my budgit to do this is curently nothing
i hope you guys can help