Questions on wired/wireless network

Hi all,

I have a question I could use expert advice on... sorry for the length, but I need to give some expositional information to set the question up.

My wife and I live above her business in an old loft. She has DSL downstairs for her business... which I have set up through an Airport Express. Problem is, connectivity is bad to non-existent for us upstairs and we don't have cable OR a phone line ran to our place upstairs, so we'd have to pay to have cable or DSL actually wired into the building.

So, we need to either tap into her DSL downstairs and run it upstairs through a router, or have our place upstairs wired for a separate account (whether it is cable or DSL - depends on installation pricing).

So, there is my dilemma; I can route the DSL through a router and then hard wire it all the way upstairs... but I'd like to run it into an Airport Express upstairs as we have a mac pro, apple tv, and her macbook that I'd like to keep wireless (I can always hard wire the Apple TV, too if need be). This would save us the cost of installation and the extra account payment each month.

If this sounds like an iffy idea in relation to consistently strong connectivity for all elements upstairs, I'd rather spend the money to set up a new account and know I'll get good connectivity then spend the money/time on a router set-up and find out after the fact the connectivity is sporadic and/or sub-par.

Make sense? Any advice from those more technically savvy than me? Thank you!

Brad