Multiple Accounts on ONE IP ?

Is it possible to have two accounts on one IP?

I want to play GW with my girlfriend, who lives in my apartment.

We share 1 cable connection, through a router.

Is it possible to have two connections, through two valid accounts, to GW through 1 ip (through a router).

If yes - another GW purchase.
If not, we share one account...

At school we are able to do so with very similar IPs.

Yes, you can even launch 2 Guild Wars on one computer (use two user sessions)

I got an official answer from GW support that states that my Comcast 4 meg cable connection should be more than sufficient to support 2 simultaneous connections. They did suggest I update the firmware on the router just in case.