Wireless Network Question

[Balrog]

I've done a bit of traveling lately, and to save on money I usually end up staying at friends or relatives' houses. Most of them have wireless networks, which is a blessing when I bring my laptop with me, however I know quite a bit are not that savvy about keeping their equipment secure and bug-free. At one of my stay's the person's computer was infected with a virus when I showed up (they contacted another friend they knew to fix the problem before I left), but just to be on the safe side I avoided connecting through their network while I was visiting.

If you have a wireless network where one or more computers are infected with a virus, worm, etc. and you keep the infected computer off while you're hooked up, is that good enough to prevent any further damage? Or can it affect the network itself in some malicious way, so that anyone attempting to connect through it gets attacked?

Admittedly my knowledge of computers is limited, so any help in this regard is appreciated.

[General Zod]

It shouldn't really matter if they're on or not unless you hook your pc up directly to the infected computer. Otherwise things like public hotspots wouldn't exist.

[Sarevok]

If you are really feeling paranoid you can set the wifi networks status to "Public".