http/fttp connection time befor logging out?

Does anyone know how long does the fttp/http connection to a website through the "My connections" stays open? how long after you loged on and did nothing with it will it log out?

The reason for me asking this is. am building a program to my website that will delete the homepage and replace it with a new one (updated one) every houres or so. Yes i am a ware that i could simple have a javascript code that will redirect the homepage to a diffrent page every few houres but, i hate javascript and i love vb so i won't use it.

http://www.northernsolutions.com/?view=product&id=1
hmm i use that and it has settings for http keep alives

http://support.microsoft.com/?kbid=813827