G'day BB,
I think your scheme sounds fine. I think you said in a post on another thread that you had a large house, 2 storey perhaps?
If there are any brick or stone walls or if the floor between storeys is concrete (you could be in a converted warehouse for all I know!) then wireless range will be adversely affected. Signals passing at an angle through that kind of material are more affected than those passing at right angles. So siting of the wireless modem/router/switch can be quite important in a large house.
Your plan to put the it somewhere in the middle, between the two fixed computers, is a good one. That will also maximise the signal for the lappy as you move it around the house.
Choice of equipment is up to you. If you think wireless range might be an issue then suss out equipment that will allow you to upgrade the antenna. A more efficient antenna (at extra cost, of course) will increase the range significantly. You would probably have to mount it remotely from the router and connect it with a cable. All the kit to do that will be provided by the manufacturer if the option is available. One of my
D-Link items had that option, though I never pursued it because range with my basic setup was ok. You can get a basic idea of what's involved if you start browsing
here.
Also, it's a good idea to keep all your equipment in the same brand and matched product lines. Many manufacturers use proprietary techniques to double the speed of wireless links (eg, my D-Link 11Mbs 802.11b network runs at 22Mbs. D-Link also does an 11g product that runs at 108Mbs instead of the nominal 54) but to get that advantage the kit at each end has to match, otherwise it will fall back to the basic standard speed.
Re the network - if you can get the internet to all the computers via your wireless modem/router/switch then you have all the communication channels you need to set up a proper network.
AA