[Retric]

There are two definitions of a bubble you can look at the current value and say the point where the market started to over value the winners at which point dell, Microsoft, and Cisco where not in a bubble prior to 1997 and it only lasted around 2-4 years.

Or you can look at the bubble from the point where explosive growth started around 1998-1990 and died in 2000.

PS: Looking only at winners distorts the picture, so while MSFT was still undervalued (relative to its current dividend adjusted price) in 1996 there were also plenty of overvalued stocks in 1996 that tanked.