We have a LinkSys RVS4000 at our ofc/lab. The router and firewall functions seem to be acceptable, though i am not sure if our sys admin ever figured out how to isolate two internal networks from each other. The VPN function requires software on the remote machine.
I feel there are two isses with this product:
1) For the VPN, Linksys provides Quick VPN, or you can buy (as in, pay for) another product such as TheGreenBow.
In my opion, QuickVPN is garbage; a less than amateur kluge that requires other kluges in your system to be able to use it and then it still does not work well.
TheGreenBow seems to work, but their support is typically french, they get back to you the next day. But they are helpful and nice, even so.
2) Linksys support requires that you have the serial number for your router unit.
If you are away from the office and cannot get the serial number, you are out of luck. It does not appear in the admin login; at least not for the version that i have it doesn't, and the firmware is up to date.
Summary:
I bought this because it comes with the remote client software. but it proved useless. So far i have not found something that integrates with the vpn functionality supposedly built into windows. So, perhaps you can find something cheaper and anyway i think you have to plan on buying a seperate client software product if you want VPN.