How many servers do google have ??

Many people (including me) ask how many servers do google really have ???
According to me the number is more than 1 Million.
Here's how i calculated it, estimates are pretty old in some cases.

• Size of google index  > 100 Million GB
• Number of users on gmail >  176 Million http://www.youtube.com/t/fact_sheet
  Considering just 0.5 Gb per account on an average (Not all of 7.xxGB is used, hence its most likely to be shared among users)
  The size is > 88 Million GB (This is much less than actual, but for the time being let it be)
• Size of youtube > 50 Million GB (>54 million registered users, which exclude the GB's of videos from educational institutions) (also see http://www.youtube.com/t/fact_sheet)

Without including Google earth (it ought be few million GB's) , picasa, and many other google products, we are aready at 200 Million GB mark .

Including all those will make us cross 300-400 million mark. And these figures are pretty old. So therefore considering a 250Gb harddisk(with around 200 Gb useable) with each server (see bigtable paper in google research labs) i feel that google has more than 1 Million servers :)