> The laptop is a Sony Vaio PCG-F403 and it has XP Pro with no service
> pack.
>
> I have connected the laptop directly to the router with a cable and it
> all worked as expected, file shares and internet.

So, is the wireless router using WEP or WPA? If so for the time being,
disable the wireless encryption on the router and card and see if the
machines can share resources with each other.

You should apply the SP 2 along with some other possible security like using
Authenticated User Group on Shares and disabling the Everyone Group.

http://labmice.techtarget.com/articl...ychecklist.htm

Duane from Reno :)