To be a bit more wordy - you can have as many idevices as you want attached to an account. I think that I have like 9... They can all have their own profiles on your computer, but they are all under the same Apple ID. Apple has NO limit on the number of iDevices that can carry content from a single Apple ID.
However, you can only have up to 5 different computers authorized to work with the same account. Unlimited devices, 5 computers...
So, just don't make a new Apple ID, and you can put as much or as little of your content on the new device(s).