Lag Spikes!!!!

[themis]

hello all.This is my first time posting here so i would like to help u all in advance for doing this.
4 days ago and while everything was working normally my computer decided to cause lag spikes on all online games when i was logged to them
(warcraft 3 , wow etc.).At first i thought that it was my hard drive cause i hadn;t formatted him for a year so i thought that this was a good chance of formatting the hd.After the format and when everything was again installed and patched i tried playing dota(war3).Lag spikes every 3-4 min etc.I am thinking that something is wrong with the router(i use WBR-3460)(LEVEL1) so i went in the settings and checked.Everything seemed fine to me.So i just reseted to default just in case smt was wrong.I installed again everything and connected as usual to the net.Tried to play again but still nth.Again lag spikes all the way.I thought maybe it was the ISP provider so i gave em a call told em what happened they checked the line and they told me that there is no noise in the line and since i download normally from the internet than the whole lag spike issue has smt to do with my software.I even upgraded my bios software and reformatted my hd but still nth.My pc is an AMD 64bit +3000 on an asus A8V deluxe 1giga RAM ddr2 400 .I am all out of ideas of what's causing this so plz feel free to suggest me anything.