openvpn

I'm considering using this for a client at work, anyone any experience with it? The client is running windows everywhere, but the microsoft VPN solution appears to rely on Win2k server (which they don't have) and hardware solutions are prohibitively expensive. Any thoughts? Of course if anyone's done this with windows *without* requiring outlay on extra software (we're looking at a winXP client, a largely win2k LAN and NAT between the LAN and the net to contend with too) I'd be interested in hearing about that too.

Sorry for the geeky nature of this post, but I can think of at least 4 or 5 of you who could possibly have done this.