we're a website that is going to have two servers behind the Firewall/Router Server (a web server and a database server). All three servers are going to be running Windows Server 2008 R2 x64.
Excuse the crudity of my diagram (I know it's not even close to being technically correct, but it hopefully makes our topology a little clearer)...

I'm currently configuring the server we want to use as a Firewall/Router/VPN, but to my great dismay it seems that ISA Server 2006 (the software I thought would be a perfect fit) isn't compatible with x64 systems.
What should I do? Is there another Microsoft solution we can use (we have a BizSpark subscription)? Should I reinstall Windows Server 2008 as x86? Is there another piece of software that we should get instead? How does RRAS fit into this?
I can imagine this must be quite a common problem, and I'm really shocked that it's nearly 2010 and Microsoft haven't released a x64 compatible update...
Thanks for any advice.