Vista vs. XP

Hi
Iv got a Xp pc witch has a printer link up (usb). I am useing wireless
to got on the net from my laptop my pc has a cable (rj45 i think that wat it
called ) to the router but when i try to connect to the pc it wont let me and
i cant share files or the priter but i had an older printer witch i conceted
to the vista laptop usein a usb cable and the xp pc can connect to that. I
thugth they then the brougth out vista its was "easyer networking " better
than xp but its not!!!

plz plz plz help me