Don't panic!! You just need to ensure all your PCs are on the same sub-net.
For example, for your sub-net (LAN) you might use 192.168.0.0 / 255.255.255.0 or 192.168.1.0 / 255.255.255.0. Typically a broadband router on these subnets would take the .1 address and then hand out 192.168.0.x (or 192.168.1.x) IP addresses to the PCs on the LAN (where x = 2 .. 254, or perhaps just a sub-range of that, say .1 to .100. or .100 to .250, etc).
(e.g If you've set for a Class C network then your are using a 255.255.255.0. subnet mask.)
The default gateway will be whatever device it is that you get out unto the Internet with. That would usually be your router. So if that had the IP address 192.168.0.1, then all the PCs should have that IP address for their default gateway.
But you haven't said what router and/or modem you are using. So you need to check against that. I have a feeling, as your haven't mentioned it, that you are not using a router. Post if you have queries.
The DNS details can normally be received by the router from the ISP and passed on to DHCP clients (the PCs, etc devices on the LAN) if they are set to "Obtain their IP details automatically" (IP addresses, default gateway, DNS, sub-net mask). So you need on check that. If the DNS details cannot be passed on automatically, then hopefull your ISP has provided details and you can enter them manually either in the router (or if not router it is possible to enter them directly into interface card in each PC).
You can find all the IP information on a PC using the "ipconfg/all" on the XP boxes. Or possibly you may need to use "winipcfg" on the 98 box.
As far a ZA is concerned. You can set it to allow put all of your sub-net in the "Trusted zone" by identifying your network address to it. Thus if your sub-net is 192.168.0.0 / 255.255.255.0 then on each PC put the address range 192.168.0.0 / 255.255.255.0 in the trusted range in ZA (adjust as appropriate for your sub-net).
For example, for your sub-net (LAN) you might use 192.168.0.0 / 255.255.255.0 or 192.168.1.0 / 255.255.255.0. Typically a broadband router on these subnets would take the .1 address and then hand out 192.168.0.x (or 192.168.1.x) IP addresses to the PCs on the LAN (where x = 2 .. 254, or perhaps just a sub-range of that, say .1 to .100. or .100 to .250, etc).
(e.g If you've set for a Class C network then your are using a 255.255.255.0. subnet mask.)
The default gateway will be whatever device it is that you get out unto the Internet with. That would usually be your router. So if that had the IP address 192.168.0.1, then all the PCs should have that IP address for their default gateway.
But you haven't said what router and/or modem you are using. So you need to check against that. I have a feeling, as your haven't mentioned it, that you are not using a router. Post if you have queries.
The DNS details can normally be received by the router from the ISP and passed on to DHCP clients (the PCs, etc devices on the LAN) if they are set to "Obtain their IP details automatically" (IP addresses, default gateway, DNS, sub-net mask). So you need on check that. If the DNS details cannot be passed on automatically, then hopefull your ISP has provided details and you can enter them manually either in the router (or if not router it is possible to enter them directly into interface card in each PC).
You can find all the IP information on a PC using the "ipconfg/all" on the XP boxes. Or possibly you may need to use "winipcfg" on the 98 box.
As far a ZA is concerned. You can set it to allow put all of your sub-net in the "Trusted zone" by identifying your network address to it. Thus if your sub-net is 192.168.0.0 / 255.255.255.0 then on each PC put the address range 192.168.0.0 / 255.255.255.0 in the trusted range in ZA (adjust as appropriate for your sub-net).