I havent been here for months, and returned to see a thread thats about wireless, oh boy what is it with Vista..
EDK has that in one, vista can cause major dramas in a network, try mixing it with xp and linux...dhcp and vista is ok, but the network can be killed by vista, then manual you say, hmmm, i wish, vista tries to do all the work for you, pity its lost in its own little world...
As edk stated, reset and restart, piece by piece, its just time not money...
If you end up with a lack of signal(and i would be inclined to find a friend who can check signal strength for you first) then a solution would be a simple little home made can antennae, place up high so its not able to be looked into or near anyones head...This little piece of gear can give a 40mw router/modem a range of up to 200m with ease...thats not bad as you can make them from a pringles tin, yes the carboard ali lined ones....
I will try to find you a link...
http://www.wlan.org.uk/antenna-page.html
This link has a few diff antennae projects...
http://flakey.info/antenna/waveguide/
This antennae wont cost the earth and can be enjoyable making...
I am in the process of making something simular, but for a range of 7 klms and of course for outdoors use..
Any modem/router with wireless has an antennae of sorts, even tho internal, just find where it is and if possible find schematics of the board, then your more than half way there, but do as EDK said first, or this may be a waste of time....