Would a phone splitter work to split my dsl between my Wii and my computer?

I have a Wii and I want to buy a Lan adapter to connect it to the internet. My Wii is on the other side of the house. I was going to get a patch cable, like the one that came with it except longer. Is it possible to use a phone splitter to connect my Wii to the internet while my dad it on the computer? Also will it slow down both connections?

No it wont, the easiest way to share it between your computer and the wii (or any other network capable device) is to buy a network router with a built in adsl modem. if you cant afford to do this, then you can still use a usb modem on the computer but you would have to set up internet sharing in windows and then run a "crossover" cable from the network card on the desktop to the lan adapter for the wii.

If your going to get a router you could get a wireless one like the netgear dg834g and connect the wii wirelessly

Have a look at the link below for more info