why do i keep lagging in halo 3 every round i play online?

[thiennguyen612]

i have dsl internet and i use xbox live through my desktop and i think i got a virus the other but i re move it but i still lag every time i play on halo and its ****ing annoying as hell. and when i look at the bars for my internet on halo it have all the bars but i kepp lagging

 

[Josh[Dropdead]]

It's probabaly the lack of internet connection of other players, or the lack of your internet connection.