connecting remote locations to a central domain

[kmatthews]

Hi All
My problem is as follows:
My company has multiple location and our ISP has just implemented a
VPN for us.

Each loaction has its own server/LAN. At any location I ping the IP
address of a device at another location EG
[Location1] 192.168.10.2 can ping [location 2] 192.168.15.8
successfully and vica versa

I however want to have a user of one workstation at location 2 login
and authenticate on the domain at location 1

SERVER [location 1]
Windows 2003 Server
IP Address: 192.168.10.2
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.10.1
DNS Server: 192.168.10.2
Domain Name : HEADOFFICE

WORKSTATION [location 2]
O/S Windows XP sp2
IP Address: 192.168.15.8
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.15.1
DNS Server: 192.168.15.2 (ie address if the server at location 2)
Domain Name : BRANCHSW

[Big Fish]

For VPN connection setup, I would suggest you to refer these threads:

How to setup VPN connection?
Tips to set up a virtual private network

It clearly indicates the steps that you need to follow in order to connect your WORKSTATION at location 2 and SERVER at location 1.