Networking issue

I've just moved, and unfortunately, its a 2 level house, with 1 bedroom upstairs and 2 on the main. . This messes with the network we've had for interweb.

If I buy a second wireless Router, and put it upstairs, while my first wireless router is plugged in to DSL on the main floor, will the second router pick up the DSL and be able to use it?

I moved from a 2-story house to another 2-story house recently.

We wired the first one in-wall so that it had ethernet jacks in almost every room (10/100, would have been easy to switch to gigabit later).  I'm still just using wireless in the new house, which has been very timely for me, considering the Wii ethernet adapter hasn't been released yet.  I will still drop cable some day.

Wired is best, but for your situation, you would be best off running one cable from your downstairs router to the second floor.  Then you could hang an AP (or a router in AP mode) off that cable and be done with it.  You'd just have to remember that you have two SSIDs to work with, one for each floor.

If you don't do this, you're looking for a wireless repeater.  These suck.  It will just extend the range of your first floor AP/router by acting as a relay for the signal.

The term you're looking for is "repeater", it's what you want if you're dedicated to going wireless. Or, failing that, centrally locate the AP in one of the two bedrooms closest to under the upstairs bedroom. Or drill a hole through the ceiling/floor in a corner of one of the bedrooms and do it that way. (Or, put it through the wall and drop it. Just don't run wireless through conduit that's used for power wires, or you'll likely be breaking electrical code.)

I use the manual method of wireless IP networking.

My computer prints out the raw packets on a line printer.  I take that downstairs and type it in manually, and then the kernel does the rest of the work. 

This gives me total control over filtering.  Plus, security is top notch.  I have hard copy logs of everything.  (You should see my basement.)  Of course, it's real slow, and prone to errors if I'm drunk or stupid, but it works.