how to bypass firewall?

i have a lan connected to internet by using a router and MS proxy 2.0.the setup is as follows:
lan subnet:141.10.x.x/24
proxy server
nic1 141.171.10.5/24
nic2 192.168.10.8/24
router
near end ip: 192.168.10.1/24
far end ip: connected to internet,class c address ,static
now if i place my win98 m/c on the subnet 192.168.10.x and put default gateway as router, i am able to ping some outside ip addresses but not able to browse sites.
what could be the problem?
what shd be done on client side?