We do exactly the same, excellent way to stop people installing crap
Had 25 brand new laptops delivered 3 weeks ago, all installed, imaged and ready to go and now everyone who takes it out has to sign a form with there name, signature, username on it including the laptops serial number that they take
They take a copy of the agreement and we take a copy, i even specifically added AOL to the list of items not allowed even after saying not to install your own software
To the OP, have a bit of consideration for the people who have to deal with these complaints every day, we don't give you the crap because we hate you, we give you the crap because there's simply not enough money to buy everyone something new EVERY time you ask for it
EDIT: well actually, some people we DO give the crap too and that is because there abusive and we hate them

personally i reserve the nicer things for the people who are nice to us and the people i beleave will be most competent in using it (EG new laptop to intelligent staff, old laptop to the dumbass thats just going to drop it getting out of there car)