Internet connection

I have 4 computers hooked up to a home network.

#1 - Main computer running XP
#2 - Laptop running Windows 98 connected to network via cable
#3 - Remote computer running XP connected via wireless
#4 - Secondary computer running Windows 98 connected via cable

I have the wireless router hooked to a hub and the hub connected to the
router to the dsl modem. All 4 computers are eventually hooked to the same
hub. I can see all 4 computer from any computer in the network and exchange
files and such. Computers 1 - 3 connect to the internet but for some reason
#4 will not. I have use the connection wizard several times and no success.
I have got the computer to connect to the internet in the past but everytime
I turn it off and I start it up again it will not connect again. What could
be causing this?

Thanks in advance