How to organize a single query to several sql servers? I need to make an inner join sql query to several SQL Servers (one is 2000 and another is 2008 R2). The query is like the following:

SELECT 
   k.ID, k.NAME, k.BIRTH, l.PROFILEID 
FROM 
   CUSTOMERS..REGISTRY k 
INNER JOIN
   SECURITY..USERS l ON K.ID = l.ID


The CUSTOMERS..REGISTRY is on the 2008 R2 and SECURITY..USERS is on the 2000 servers. The servers are situated in different networks, connected through internet. Is there any way to organize such query?
The servers are situated in different networks, connected through
  internet.


Preferably, don't do that. 

VPN and (as AceCTO suggested) linked servers if you must but if this is a query you want to run regularly, move the data. BCP it, replicate it, log ship it... just move it.