first of all using .ppt here is a bad idea, not everyone can see those and cant be bothered to convert them..... simple jpg,gif are far better.
extending your wireless range is simple, you dont need wireless routers, any cheap wireless AP will do in the speed range and freq you want to use, just spread them out to were you want them to cover, then single ethernet wire them all into a central and cheap (1gig is best long term,but now esential OC,unless you are going to use 11N kit with 1 gig wired ports included anytime in the future)switch...
keep one master wireless router as your DHCP server to give out IPs in the range you want, or better, as already said, hand out fixed IPs to the Mac's, or manually assign them to each extra AP/router.
when its done right you can even use the spare WAN ports on these wireless routers (see theres always a good side to everything
) to attach some isolated
FreeNAS fileservers in another room in the house,in the loft for instance, for all your remote file storage, ISCSI is the fastest ethernet protocol to use for that BTW....(over that 1gig wired LAN server section OC)
OC the No.1 reason to hardwire any extra wireless routers/AP's into the same Ip range, is your not then using up the valuable wireless bandwidth to link them together as you might with
WDS mode.
this is a very old argument
but keeping as much data off the wireless part can only be a good thing, so a simple wired star config into a wired switch of any extra wireless AP/routers will serve you really well.
as will fitting new directional arials to keep the noise down, something as simple as a bit of foil shaped in a half circle on cardboard backing and hole at the focus point sliped over your current fitted AP/router arials works well too
google DIY wireless arials to see many versions on the cheap ...