The stock cooler is not that bad really when it comes to cooling, noise is another matter though. What is bad is the temperature control with it. Setting the stock fan to 60%, let alone 100% really cools the card well, but the automatic fan control never really goes up to those levels, letting the card cook. I think ATI was afraid of the large number of complaining users regarding noise etc. The stock cooler is fine, but it should rev up more when you hit 80+ degrees and be a lot quieter.
I have fitted my X2 right as well - yay for me.