REMOTE CONNECTIONS USING WINDOWS XP PRO

HI MEMBERS,

I HAVE A PROBLEM AND I NEED SOLUTION FAST.SO PLS HELP ME.

I AM TRYING TO CONNECT TWO OFICES IN DIFFERENT LOCATIONS TOGETHER TO SHARE DATA ETC.

THE COMPUTERS ARE USING WIN XP PRO WORKSTATIONS.
THEY BOTH HAVE ADSL MODEMS AND ROUTERS.

ONE SITE HAS A STATIC IP BUT THE OTHER DOES NOT THEY ARE BOTH ON THE SAME ISP PROVIDER.

WHAT SHOULD I DO? PLEASE