1. I need Windows Server 2003 to use WINS

No.. Windows NT Server - Windows 2003 Server can be used for that... I am unsure of any 3rd party WINS Servers

If there are multiple subnets I need a server on each subnet.(It will work if I use Windows XP Pro as server on each subnet?)

When I say server I am talking something that is capibable of running a WINS Server service

I saw once a network with 4 subnets and Linux as server (the only server in that network;no server on each subnet). Is it linux better than Windows Server 2000/2003?

Unsure... I don't know linux well enough to answer that question

I will try to enable the forwarding of NetBIOS broadcasts. I think I know how to do it in Kerio Winroute. It is something like NAT?????

It is not NAT. More like an acl (access control list) most ACL's are similar (sorta). It is more like port forwarding in a firewall but to a subnet and not a specific computer

In firewall I have this two options:

-Source NAT

-Destination NAT(Port Mapping). I think here i have to do something but I don't know how. I need some help here.

I dont beleive it would be either... if it is a firewall... there should be a set of rules... NAT is just translating an external IP to an internal IP.... which is sorta a rule but there should be something like .....(And I am pulling these terms off Kerio's crappy knowledge base) "Network Security Rules" "Application Rules" "Custom Packet Filter rules"

They have a spot on their site where you can create a trouble ticket... http://support.kerio.com/?_a=tickets&_m=submit I dont know kerio at all to be able to tell you how to do that. Firewalls tend to have a generic-ness to them where you can work your way around and know what the rules do and dont do but as to where to find them in the firewall... it is just a matter of hunting around