Thanks a lot guys
I asked this question, because these days almost everyday i perform live update in Norton's anti-virus 2006, it is finding new definitions,.. in which case, in 1 week i have added quite some new definitions, which always prompts me to run it..
The same with adaware, spybot, spyware doctor.. though not everyday you find new definitions atleast once a week, ,.. which made me feel , every week-end i have to update all definitions and run all the software..
Thanks