Airport Express vs other Wireless N routers

I live with housemates and we need internet + wireless access to it. I have 2 housemates in a small house. I watch netflix streaming movies fairly often and do not want it to kill the internet speed for my other two housemates.

My housemate is buying the router and has a max of about $100 to spend. Are there good reasons to buy a linksys or something in that price range over an Airport Express? I expect the Airport Express probably has less range? But by how much and whether or not speed or quality of signal within that range would be lower is something I have no idea about.

Can anyone shed some light on this topic for me? I'd prefer an Airport Express, but if it would be slower for people than a linksys of same price, then perhaps the Linksys'd be better. She can't afford the Airport Extreme.

I'm wireless N but I doubt the other two are. Would their being G make the router switch completely to G or would it be able to give me N while they get G?

If the latter was the case, I could just put it in a place in the house that is closer to them while I do just great with my N access.

Aside from that though, is the Airport Express really as "powerful" as other N routers? I would think since it's smaller it must have smaller or fewer or whatever antennae. For example, why would someone drop the coin for an Aiport Extreme unless it was a lot more powerful than the Express which is like half the price?

Just curious. If you all say the Airport Express should be plenty powerful for a small house then I'll take word for it, but I am curious what, if any, it's disadvantages would be relative to something larger like a Linksys or D-link N router.