|daytek your question started with do I need rras and vpn.|
You may have had the link I provided bookmarked but it does not appear you understand the material. I say this because you appeared surprised that you need two nics in the server to do a rras vpn. This also indicates to me you didn't do your homework concerning the project before you jumped in buying equipment and configuring the server.
Hopefully what follows with clarify things for you.
VPN is a secure tunnel thru the internet to either connect sites together or allow users on the road with internet access to logon/authenicate to the vpn router to then gain access to network resources. I gave examples in my previous post concerning each.
Site to site vpn - done ONLY with hardware vpn routers/firewall appliances. You can, depending on unit, supply both site to site vpns as well as remote client access. A site to site vpn provides the same services as a Point to Point T1 or a Frame Relay T1 does but uses the internet instead.
Client vpn access - is where you install software on a laptop/notebook/pc that goes out thru the internet and authenicates to your vpn router and thereby gains access to the network resources. An example of this usage are road warriors or I have two sites with only two people part time. Instead of creating site to site vpns we just have then do the vpn client thing to connect to our network.
Next you have a software VPN. This is what RRAS is about. Example 5 in the link I provided gives you a diagram of what you need physically to establish a site to site vpn using RRAS. If you want to use RRAS you do not need vpn routers.
Here is an important rule of the road concerning computing projects. Hardware is always faster/better than software.
What this means is given your scenerio I would put in vpn routers before I would install RRAS. You use software solutions when you can't afford hardware solutions.
Hopefully this will answer your question of do you need both at same time.