Windows 7 , PPTP VPN error 807 and 800

[zillah]

Dear Experts

Please don't steer the topic from PPTP to IPsec and other types of VPN which is more secure than PPTP,,,,etc

I have got this scenario windows 7 is acting as vpn client at home and windows XP is acting as vpn server at work.

At home (LAN address is 192.168.10.x/24)And I configured windows 7 as VPN client same as here :

http://www.hideipvpn.com/2009/09/howto-windows-7-pptp-vpn-setup-tutorial/


At work (LAN address is 192.168.1.x/24) I configured XP SP3 as VPN server same as here (except I could not enable PPTP Passthrough on my router because I could not find that option) :

http://www.home-network-help.com/pptp-vpn-server.html

Please be aware
On the vpn server, I have selected administrator as username to be allowed for vpn, subnet that vpn server is using, is : 192.168.1.70-73

On the vpn client I am using the correct username/password.

Security I tried below combinations with no joy:

Type of VPN : Automatic,,,,,,error 800
Data encryption: Optional encryption (connect even if no encryption)

Type of VPN: Point to Point Tunneling Protocol (PPTP),,,,,error 807
Data encryption: Optional encryption (connect even if no encryption)


Router that I am using at work (where XP is connected to it) is :

2wire router with below details :

IModel: 2701HGV-W Gateway
Hardware Version: 2701-100655-004
Software Version: 5.29.113.16

Port forwarding 1723 was enabled

Whenever I try to establish a vpn tunnel I am receiving either error 807 or 800

Note:
The VPN server (work deskto) was working when I had at home VPN client as an XP OS not windows 7, but when I upgraded from XP to windows 7 I lost my vpn connection.


Thanks

[zillah]

Now I have got couple of question :

1- Do I need to enable GRE Protocol 47 (PPTP Pass Through or VPN Pass Through) as well, when I read couple of online threads they suggested to enable VPN Pass Through (GRE Protocol 47) with some nasty routers

http://www.chicagotech.net/vpnsetup.htm

2- I had not enabled GRE Protocol 47 (PPTP Pass Through or VPN Pass Through)when I had XP as client before upgrading to windows 7

3- If option 1 is not necessary what could cause this problem ?