It is not a matter of which one will work better. It is the same software under a different licensing regime. OEM is cheaper but the license is for a new computer and technically is married to that computer from that time forth. This is to allow system builders to make machines at competitive prices. The full retail can go on any machine you want but must never be on two machines at one time. Full retail of course costs more. Now when it comes to specifically to the issue of using Win 7 in a Server Network Environment you need either Win 7 Professional or Ultimate. Starter and Home Premium do not work in a Server environment. The laptops you have should have their own OEM software already. If not you need to buy Full Retail or in your case potentially Volume Licensing to replace the OS for them all. Best thing to do is contact Micrsoft and check out what is the cheapest option.