networking 2000 and XP

[amy]

I have a desktop running on XP and a laptop running on
2000. I have the laptop connecting to the internet
through a wireless router (and this works fine), however
I am unable to share files. The laptop recognizes the
desktop but the desktop doesn't recognize the laptop. I
tried networking with the XP software (it says put the XP
CD in remote computer, which i did) however it says the
networking function only works with 98 and
millenium...Does anyone know how I can share files given
i seem to have incompatible operation systems?

THANKS!