Best bet is one of
these or
these or
these.
Buy it before hand and place it in your room. Fire it up and see if the wireless lappy can get signal where it needs to be, if that works then you can cable to it and then you'll only need a pcmcia wireless card for the win98 lappy (£10-20).
If you cannot get a signal to the laptop then find a place that does and then you'll have to site the cable modem there and either run a network cable to your pc or get a pci wireless card for your pc.
hth
hm
edit It could be the perfect excuse to get one of
these babies
As for the hints, get it installed and bin the disc. Theres instructions on here for getting it running with-out ntls software. once running on one pc simply unplug the power ethernet to the router and then to the pc and all should be working. Tweeak your router with a meaning full ssid then get your laptops to connect. once they are all connected you can set-up whatever security you need on the router safe in the knowledge that you can at least resort to it working.