PP......
".....but what was that about critical errors?"
With the best will in the world one is going to get day to day hiccups with Windows and associated programs and it is these that that generate the error messages. Invariably they sort themselves out fairly rapidly (99% of the time a reboot will solve it) but there is a fair amount of scepticism about the need to inform Microsoft (or whether there is anyone there to receive it!). Hence.....
.....eliminates the irritant but at the same time keeps you informed of the reason for any (hopefully rare) major PC meltdown.
With just the above enabled I was informed the one and only time I had a major crisis (all the other 'fluff' sidelined).
Don't forget you can get a far better real time overview of what's going on - including errors for which you have disabled 'error reporting' - via (in XP):
Start > Administrative Tools (if enabled) > Event Viewer > Application
Start > Administrative Tools (if enabled) > Event Viewer > Security
Start > Administrative Tools (if enabled) > Event Viewer > System
Start > Administrative Tools (if enabled) > Event Viewer > Internet Explorer (if you have IE7)