Sharing an Internet Connection

I recently setup a small office network with a Compaq Windows XP as my front end machine, another XP machine and a Win 98 Laptop running in two other rooms. The 'other' XP has it's own phone connection for Internet but the Laptop needs to connect through the network. I'm using a Compaq iPAQ-CP_2E Router with no problems sharing files. The only problem I'm having is I cannot get on-line with the Laptop. Even with both XP machines already on-line.