If there are any NXTs in the list you will never use, I suggest removing them. I don't know if it really makes any difference in this case, but in the case of COM ports (or virtual COM like NXT>computer BT), you can't exceed 256 devices.
And even if you do uninstall a couple extra NXTs from the list, it will just take a bit longer next time you connect with USB (the computer will need to "install device drivers", which is automatic in Win 7).
