OK, I'll help confuse you more. The network info given above about wireless/wired and routers is good. You can get your DSL to other pieces of equipment in your house pretty easily if you don't want to run any new wires. That being said, wired is always better.

If you go wireless (Wifi aka 802.11a/b/g/n)
If you put a wireless router onto your DSL modem, all your networkable equipment can connect to the internet easily. The only caveat is that your equipment needs to talk to the wireless router via wifi (wireless). If that equipment isn't wireless, you can buy adapters to make them wireless but then it gets pricey, hence the end answer to always go wired…

You didn't mention what equipment you'd want to connect so I'll assume say a PS3 or Blu Ray player with ethernet, a set top box (like a Tivo) with ethernet, and a networked AVR. Here you have 3 pieces of equipment that need a 'wire'. You can buy 3 wireless adapters but that's pricey. OR you can buy one wireless box that can handle 3 wired ports and then connect wirelessly to the main router on your DSL modem. See the Apple article below on how they do it w/ Apple equipment (this is how I do it w/ my Tivo and Slingbox in a distant room). The picture is worth the thousand words.

Apple and the WDS network - http://support.apple.com/kb/HT2044

Yeah, the Apple routers may be a bit pricey but I think some other vendors like Linksys and Dlink may do the same, but Apple's easier to setup and there's enough fanboys (like me) that post on various support forums to make setup easier. Using this method, you can provide multiple ethernet ports to any location using a wireless link between multiple routers. This will save you from wiring multiple cables.

If you go wired
You can use something called Powerline Ethernet. Use the AC wiring in your house to carry ethernet. Connectivity can be a problem if the wiring in different rooms crosses a transformer or if your power isn't clean. Barring that, it's a good solution. I use several in my house to hard wire some Tivos so they can transfer shows between boxes via wired (which is always faster than wireless). You connect one adapter to your router and another one where your equipment exists. They have 1 port and 4 port versions. I use the Netgear version but there are others. The beauty here is that it is pretty much plug and play, almost no additional configuration required. Think of it as using your AC wiring as ethernet extension cables.

http://netgear.com/Products/PowerlineNetworking/PowerlineEthernetAdapters.aspx