Not really, unless they install it too. If you paid to have it delivered, you've paid enough. If you didn't pay any delivery, then it's up to you. If they just delivered it and that's it, then they get paid enough. If they set it all up for you and showed you how to use it, then maybe. Otherwise, no.
If I was a delivery guy I would not expect to receive a tip. I am however a woodcutter and sell firewood, sometimes someone that buys the wood does give me a tip, and its a really nice gesture and experiance cause I do not expect one. So if you want to tip them go ahead its really nice when its not expected but it is not necessary.