If this is a new home then you should be doing this right which means that now is the time to do some SERIOUS research. Let the wife pick the paint and carpet color, focus on the guy stuff...
A/V cabling, network cabling, house distributed audio & video & control... CONDUIT.
Networking requires an active splitter, called a router, which is typically located at a central point in your home. It doesn't need to be in your office, but can be in a storage room in your basement... in fact, that's typically a pretty good location for it.
The cable connection for your modem comes to this location and the modem lives next to the router. Then the router connects to as many LAN ports as you have in your home.
For example, my home has one LAN port in each bedroom (5) plus one in the family room, study, and rec room. So, a total of 8 LAN ports in my home.
Cable comes from outside to my basement equipment location...
I split the cable out to my house (a bunch of cable jacks throughout the house)
and one of the feeds goes to the cable (actually FIOS) modem.
Then from the modem into a 8-port router.
http://www.newegg.com/Product/Product.aspx?Item=N82E16833124022
There are modems available which have a built in router (nice) but tpically only have 4 ports.
If you don't have enough ports on the router, you can add a network 'switch' after the router...
http://www.newegg.com/Product/Product.aspx?Item=N82E16833130048
That will give you up to 16 WIRED LAN connections throughout your home.
There's a bit of a learning curve to get it all figured out and you can pay someone to assist you or you can come back to sites like this one, or other more network specific sites to help you get things figured out.
There is a significant value to have an entire home properly wired for networking as well as audio and video. One of the nicest things you can do is add conduit from a basement equipment location to your attic so that wiring can be added later if you want to. I ran two pieces of 2" conduit from basement to attic for about $200 and have run a number of cables to my attic for audio, video, and antennas which I have in my attic. If I had to cut open walls to get the cabling run it would have cost hundreds in repairs.
Just some stuff to consider!