have: desktop, and misc. want: wireless network

I have a desktop w/wi-fi pci adapter, and I want to use that to make an ad-hoc home wireless network (instead of getting a router); I have a laptop and pda. Obviously these are all new toys, the reason I'm asking this question;
Is there a tutorial or something (other than my help and support) that could walk me through this?

If it helps the desktop and laptop have vista and the pda has windows mobile 6.
thanks.