of course you can block them with a firewall!!!
here is ipchains:
ipchains -A input -s ***.***.***.*** -j DENY
iptables:
iptables -A INPUT -s ***.***.***.*** -j DENY
replace ***.***.***.*** with the IP address of the server you want to block. You might want to swithc the "input" to "output" if you want want to stop your computer from even contacting the site.
[ October 16, 2002: Message edited by: The Master of Reality / Bob ]