Recently travelled through MCO from the UK. The security process there is farcical (on top of the normal slow process at US Immigration & Customs) , but I didn't see anybody being refused entry with a laptop. You may well have to get it out/power it up etc.
As illuded to above though, do be prepared for a wait due to the TSA carrying out a security check on you *after* you have left the a/c! (completely bizarre job creation scheme as far as I can see)
You will also have to re-claim your bags twice.
Took us about 1.5 hrs after arrival to get processed, but I've heard it can be a lot worse
