As title suggests, the traditional IT tasks like computer requisitions, mirroring, hardware, set up, Helpdesk. I'd love to know who does it swimmingly and why.
Your question seems to be focused on the hardware infrastructure side of things? But then you mention 'help-desk' and that suggests you are asking about buying and supporting masses of PCs.<p>I am a data center guy, so I would suggest Google being one of the best at designing, building and running massive numbers of computers. Of course, they don't exactly follow the IBM/MS 'traditional IT' model.