Okay, I think there needs to be another opinion added here.
First of all, I feel it is, in many cases, inaccurate to say that there are basically no differences between something like
OpenVPN versus router/firewalls with VPN functionality built into the them.
I can tell you from experience having sold and configured that gear (most notably Zyxel), that there are some
significant differences in some of the gear (and no, not just the very high-end gear.) The Zyxel (and other)
models I sold, as well as other low to mid-priced brands had a built-in hardware co-processor to process VPN
traffic, thereby taking the load off the main CPU. Of course, this doesn't apply to all of the very cheapest
consumer grade models.
That co-processor was essential for situations in which VPN traffice was moderate to heavy. I can't say for sure,
but I don't believe older PC CPU (unless it's dedicated only to that task) would be up to the task.
Second of all, you get phone support via some of the vendors. I'm sorry, but setting up a properly configured
(IPSEC) VPN is not always as easy as it looks, though the open source software definitely is a big improvement.
Also, don't underestimate the convenience of having VPN server/endpoint and firewall router all in the same box
and IP address. It's a great convenience, from my experience. Of course, I know security folks
will tell me that's just bad policy security-wise.
Finally, taking a brief glance at OpenVPN's HOWTO, I just can't see someone without intermediate-level networking
knowledge setting that up. If I'm misled, great-please show me a link so I can inform others.