Why do i get like 3 second lagspikes every minute?

Well i just bought this BRAND NEW Asus laptop! I'm not using WIRELESS, im connected directly to the modem! And i am having 3 second lag spikes on games and ventrilo! Its not like my computer freezes but everyone stays in place and people on ventrilo stop talking for like 3 seconds! Like on WoW for example. When i get the lag spike people stop moving but i can still move! So its not that my computer freezes