Connecting Linksys Wireless to Apple Airport Extreme wireles

I have a XP PC network with a Linksys wireless Router WRT54G that is across the street from our Apple Airport Extreme wireless router connected to our server. I want to connect the two routers so that we can share the data on the server wirelessly. Tried VPNing it but the proprietary software we use is too bulky and takes to long to load the data via wireless VPN, so any ideas on how to connect the two networks wirelessly. Thanks in advance!

Robert
rhammerman@aol.com