Connecting one computer running XP to two different networks

at the same time?
if not one NIC is fine.  Just join the domain, it will make a seperate profile though.
You need to have permission to join a forign pc to a domain.  usually a domain admin account is used.
if you create a username/pw identical to your domain logon, you can make it part of a workgroup that is the same name as your domain.
This will give you limited network access.

yes at same time

oh.
much tougher.  A vpn is the easyest solution if its accessable.

are all 3 computers at the same location?  is the cat5 cable directly connecting the 2 computers?  if it is then it is a cross over cable.  How many computers are we talking about?  is it a hub or a switch?

when you say that you would like to connect the first machine to the office network, do you know if the office is running a domain or a workgroup?  are you using dhcp?  what is the addressing schemes?  what machines have internet access?

he wants them connected at the same time.  So he cannot be connected to two domains or a domain  and workgroup at the same time I dont think.   maybe with 3rd party software?  A vpn would provide an option to logon to a seperate network...  But I am not sure how to logon to two seperate networks at the same time.

Note: i have no idea why you would want to either.  Its a security risk also.

maybe I am missing something

If XP Home edition, you CANNOT join Windows domains, only workgroups.  Instructions follow:

Windows XP Home

http://www.lpt.com/windowsnetworking/regusers/wxphdoms.htm

Windows XP Pro

http://www.lpt.com/windowsnetworking/regusers/wxpjoind.htm

Here is the situation.  I have computer #1 which is a dedicated machine which runs a photo processing machine.  Computer is hidden behind a front end specialized package.  Computer #2 connects to computer #1 and a workgroup is set up so that computer #2 is used as a workflow station.  Data is sent from computer #2 to computer #1 for processing.  I would also like to hook computer #2 up to my office network so that I can access files from my server and access to the internet is through this server as well.  Is it possible to do this?

You mean add another network card, or plug all machines to the same hub (computer #1 and #2) ?

Add another network card and configure computer #2 to see both workgroups

A computer can only be a member of one workgroup or one domain simultaneously, although with 2 NICs you should still be able to file share on both, as long as you make sure NetBIOS is bound to BOTH adapters.

It would be easier if you just connected everything to the same hub, so do this if at all possible.

Are machines XP Home or XP Pro ?

XP Home but I could upgrade if needed.

If I connect both computers to a hub what would then be involved?

Did you ever say if your office network is in the same physical location as pc1 and pc2?

just making sure.

is your office network a domain or workgroup?  Are you an adminisitrator of that network?