I've had IBM Thinkpads with wireless conectivity for years (obviously because I work for IBM). I can sit in my garden at home and access the Interweb or sit in my bedroom and access the latest builds of Lotus Notes. But the one thing I have never managed to do is print to the printer connected to my home PC. For some reason my home PC has never been able to see my Thinkpad across my wireless network.
Eventually I asked my top mate Matt to have a look to see if he could find the problem. I'm glad to say that I had got the basics right so I wasn't being a total Muppet. The problem, it turned our, was that I was using Zone Labs for Firewall and Anti Virus but the "Net Firewall Services" was also enabled, presumably after I installed XP SP2. Turning this off didn't compromise security in any way but it allowed me to print from my laptop.
So now I can sit working in the garden and send documents to the printer. I think it is brilliant but our cats, Barney and Boo, think the printer is possesed.