Remember that every split adds additional loss to the incoming signal level. A 2-way will lose 3.5 dB per leg, a 3-way 7 dB per leg, and a 4-way typically 11 dB per leg. Losses are cummulative as well so one leg of a 2-way connected to the input of a 3-way will lose 3.5+7 = 10.5 db at the output of the 3-way (in other words the same as just using a single 4-way).
You want to minimize splits as much as possible and/or use an amplifier where necessary. Of course it all depends on having the incoming signal level from the cable provider at an appropriate level - which is the cable company's job and they will come out and check things if you ask.
From the description of that bi-directional amplifier link:
It is recommend a cable or telephony modem should be placed on a separate network segment from the amplifier as incorrectly amplifying or adding to[sic] great of a signal level may cause damage to the cable or telephony modem.
In general that is true and as a rule of thumb you don't want to amplify the leg going to the modem. My house is wired to a central wiring closet in the master bathroom closet and has eight cable outlets around the house.
I split the incoming feed with a 2-way splitter and one leg goes straight to the jack in my office where the modem resides (and is thus unamplified but loses a tiny 3.5 dB from the split) and the other leg goes into an 8-way 4 dB amplifier which feeds all the other jacks in the house. So basically, the cable jacks lose 3.5 dB from the inital split and then the amplifier adds back 4 dB for an effective 'no-op' - as long as the incoming level from the cable company is sufficient every outlet in the house works fine - and they do.
