Iphone

I'm trying to setup a VPN between my home network and my office. I can remote desktop to (1) fine from (6), forwarding TCP 3389 in router (2) just fine.

-----------------------HOME-------------------------------- Internet --------------------------- Office ----------------------------
1. XP sp2 ----- 2. BEFSR81 ----- 3. Cable Modem ----- Internet ----- 4. Verison DSL ----- 5. DLink Router ----- 6. XP sp2

1. XP Pro VPN Server, Static IP, Windows Firewall Ports TCP 1723, UDP 500 open
2. Linksys Befsr81 v.3 latest firmware. PPTP forwarding enabled, forwarding 1723, 500 to xp vpn server
3. Comcast RCA modem model unknown for now
4. Verison Westel DSL Modem
5. DLink router, model unknown
6. my office XP Pro sp2

I know there is NAT taking place between (1) and (2). I don't want to place a single machine in the Linksys DMZ. The error I'm getting when I try to connect to (1) from (6) is 800. The VPN connection doesn't even seem to see the router (2).

Have tried to find an answer in this database, so now I ask the question. what am I missing?

Iphone

I see you've opened up port 1723 TCP which is used for PPTP connections and port 500 UDP which is for IPSec connections, please verify which one you really need to have opened up. (and also, please mention which location you're using as a server)
Apart from this, I'm guessing that both Windows XP computers are in the 192.168.1.x subnet which will cause your VPN not to work, please move one of them out of that range by changing the local subnet on one end.