Here is a guide on setting up the VPN.  I did not follow all of this guys advice as he was doing more than I needed.  The tricky part for me was that there required a second NIC for the VPN.  In 2003 I was able to setup both the regular network connection and the VPN on the same NIC.  Not true for 2008.  Get a second NIC on the server and use it for the incoming VPN requests.  

Second, your ISA server should be just like any other firewall.  Make sure the ports are forwarded through it to the Server 2008.  The ports you need should be on the article but mainly 1723.

You could also set it up with VPN routers on both ends...this would eliminate the server setup need and bypasses the firewall as well...though it can be tricky since every router setup is different.

Good luck,

Todd

Hi Todd, thanks for the help.
Should the additional "VPN" NIC be installed in the ISA box or the 2008 Server box?
If installing in the 2008 Server box, should it be connected back to the ISA box again?  On top of the existing LAN link between ISA & Server 2008?

oops...looks like I never posted the original link.  here it is...

http://www.windowsecurity.com/articles/Configuring-Windows-Server-2008-Remote-Access-SSL-VPN-Server-Part2.html

Hi Qlemo;
In response to your post;

Our TMG already has two NICs, one for external & another for internal.   Is this the config you are referring to?

It is behind a NATTED router, but the router has a public IP mapped directly to the TMG box.
We are already using the public IP via this router for RDP sessions into the Windows 2008 box, so our router NATs, etc. via TMG is working.

From your comment;  "The best result is always achieved when the devices connected to the Internet manage VPNs"  ... Unfortunately we are using an ISP router, which is blocked for any additional setting changes or functionality, apart from additional NATs we may require.  

The VPN will be ocnfigured on the TMG box and not the Win2008 box?

On the remote site, they are using a Checkpoing R65 firewall with IPSEC, which is independantly configured and managed.  Will it be possible to configure the TMG to dalk to the router config in the remote site?

Since the TMG is facing the public IP (even if NATted), you should set up the VPN there. The ISA/TMG has more VPN options than W2008, so it is your choice anyways. BUT Checkpoint is special - recent releases should be able to terminate a standard IPSec tunnel, but previous were not, and required to use the Checkpoint-One SecuRemote client.

Looking around, I found some working examples using ISA 2004 against CP NG or R55, so I suppose it should not be a big deal. One configuration example can be seen here: http://www.redline-software.com/eng/support/articles/isaserver/general/implementing_checkpoint_ng_r55_firewall_and_microsoft_isa_2004.php .

I see the article of Thomas Shinder "Configuring Windows Server 2008 as a Remote Access SSL VPN Server (Part 2)", refers to a request for a machine certificate from a local enterprise CA, BEFORE the RRAS installation.

Our DC (Win2008) and the TMG already has a public certificate installed for Exchange.  Does this mean that an additional certificate should be requested / installed, or will the current certificate and FQDN suffice?

A SSL VPN is completely different from IPSec. Sorry I didn't have a look yet on that link. A SSL VPN needs a valid certificate, on which both sides can agree as trusted. And in this particular (and most other) configurations, you are setting up a dial-in VPN - client-to-site, not site-to-site.

Thanks Qlemo,
I just went through the article you posted.  And you are correct, it does not involve setting up SSL, but IPSec tunnel mode.  I will configure this on the TMG and see how it goes.  I noticed the last phase is for configuring the VPN access rule and it relates to the site-to-site custom needs.  Could you perhaps give me an example for this access-rule?  I assume this rule destination will be the Win2008 server?

The rule is allowing access *from* a network or single IP *to* a network or single IP. You need to put in whatever you think is correct ;-).