I'd probably count for four, but if it counts as a new installation each time you format, than more than double that. (No more now though, I've got a Mac. 3) I'd assume it's the same for many users here.
I wish I could take credit for this... It showed up in my mailbox about ten years ago.
What Happens When Engineers think too much about Christmas...
As in certain cults it is possible to kill a process if you know its true name. -- Ken Thompson and Dennis M. Ritchie