I have a Netgear DG814 router and have setup everything fine (I think). I have entered Plus Net's DNS server addresses into my router and assumed that all the clients on my LAN would pick this up from the router - however when I tried to browse to a site, nothing would be displayed. I then configured each PC with Plus Net's DNS server addresses and I cold browse to sites, no problems. I figure I must have setup something wrong in the router? - Is is something to do with the DHCP in the actual router?
I am not familiar with the netgear, but if you are not using dhcp internally then the client machines will not be given dns and gateway settings (along with their ip) automatically. Therefore if you are assigning fixed Ips you should assign gateway and dns too. - So your 'fix' is the correct one in this scenario