ok...im mad

and confused...
i have a new dell...4 mabe 5 months old...i got a celeron d proccessor

but my question is
my brother has a dell...4 years old...pentium 4 proceesor...we use linksys wireless networking. my brother can play gunz fine on his computer...but i cant play at all...our parents comp firewall is turned off...and im confused...he plays w/o lag but i always get them errors...can any1 tell me y?