I have a the main cable line coming into the house. Then there is a 4-way splitter sending it to all of the 3 TV's and 1 Broadband Internet Connection. The cable guy told me that the splitter was the BEST you could get, as you did not want to use a splitter with amplifier because I think he said something about it interfering with the Video On Demand & High Definition Channels. He also told me this splitter was the the that was highly recommended for HD & Video ON Demand. The splitter says its a 5-1000Mhz, with -7db for OUT to TV's and 120dB EMI Isolation. I'm having a little problem with VOD working and my Internet seems to be a little sluggish, but mainly its the VOD. Is this the BEST 4 way splitter I can get that is works with High Definition & Video On Demand or are there some out I can pick up locally to put in its place. The cable company I am using is Comcast in Jacksonville, Florida.

Retails at around $30-40. Monster make a decent one.
You might also want to try a two-way splitter first; one going to your broadband, the other to a 4-way (haven't seen a 2GHZ 3-way) for your TV's.

or buy a good commercial one. The tricky part will be finding a good one for 75 ohms.

http://www.pulsarmicrowave.com/products/power_dividers/4-way_stripline.htm is a good place to start. The only thing I'd look out for is the isolation that you will need for your cable modem, it is possible that it could dump some power into your TV or anything else that's hooked up to the combiner. Don't put an amplifier anywhere in the way of the cable modem - I.E. in the main cable line, or in the line coming off of the splitter to the cable modem. Amplifiers are active components that only work in one direction. To amplify a signal for a cable modem you will need a Bi-Directional amplifier, which are a PITA to design and can be quite expensive.