Handling Multiple Jquery functions

Handling Multiple Jquery functions

Hi guys sorta new to jquery

i was having some problems with updating my using jquery i have 2 onload xmlhttprequests that trigger every 20 and 30 seconds

and i also have tabs on a footer bar that open a new request.

i have everything working ive loaded my site on firefox and internet explorer and sometimes the divs that display the refreshing content get mixed up with each other.

im thinking i have to many requests open. since theres about 15 tabs on the bottom when you click it , you set a interval for 2 seconds, how can i make it so
after you click the tab and click it again the script turns off ?  so i dont have to many requests sending.

is there like a queuing type of system ? sorry if i sound so new.