Probably as many times as I've had hot dinners or as many mm there are in a "standard piece of string".
However I think my current setups are going to be stable now
( 2X Enterprise X-64, 1X Pro x-64, 1X pro x-86, 5X home premium x-64)
Did a lot of work in last 2 weeks getting our home network all up running with fixes etc.
Am now busy in switching from SUSE server to W2008 R2 server for the main server.