networking question

Given my complete ignorance on networking matters, I thought I should come straight away to the forum to ask this question.

Right now we have two computers at home, my iMac and my girlfriend's windows laptop. Both connect wirelessly to a speedtouch modem and router (through which they connect to the internet). Would it be it possible to create another wireless network between the two computers? (from time to time we need to exchange files etc, plus there's a serial printer which we can only connect to the laptop) If yes, how could this be done?

I would appreciate your advice on this, thanks.

thanks! The guide was really useful, so I tried to do that. I had some weird results though (I think).

I could log on to the win laptop using either the password for the share on the laptop or the password to my account on my mac. That shouldn't happen I guess, but isn't it strange that it does happen?

Anyways, sharing files works on the win laptop now. Um, how safe is this? I mean is there any particular security issue I should pay attention to?

Also I couldn't get my mac to see the printer which is connected to the laptop.