I would say that it depends on how many times you are dividing the signal. If you are just going through a 2-1 splitter than you are cool, no noticeable signal degredation. If you are wiring the 'west wing' of the house with mutiple additions with long cable runs, then an amp might be helpful.
I just did this last weekend, I upped the number of cable outlets from 3 to 5 and I felt an amplifier would be beneficial to my situation, so I added it. I notice no difference, but I didn't try it using a passive splitter.
You can always add the passive splitter and then add the amp later on if you need it. Keep in mind that the amp needs 110 VAC, so you will have to have it near an outlet or bring power to it.
Good Luck
