Setting up an Access Point.

[tidnab]

We have a Netgear router which is downstairs and has 4 available Ethernet ports. Trouble are there are 5 of us living here, 2 upstairs and 3 downstairs. We were thinking that 3 downstairs could have 3 of the 4 ports, and then use the 4th port to connect to an access point upstairs.

The 2 upstairs would also be using Ethernet cables in order to connect to the access point. So essentially everything is wired to something.
Apologies if this doesn't make much sense.

My question is: How would the service upstairs differ from the ones downstairs? Would they be slower, or perhaps not have access to the HUB settings (192.168.0.1)? And also what sort of router/hub/switch/access point should I buy for the upstairs? :S