I was playing with a new Linux filesystem. My code passed a null pointer into the Linux virtual file system core code. That code took an oops and died. The rest of Linux, however, continued on with no awareness that the filesystem code was kaput. The Linux kernel subsystems are properly isolated from one another. EVERYthing on the system that did not need file access was totally unaffected by my code error.

On Windows, many things have been moved into the operating system area for marketing reasons -- to make things 5% faster or 2% faster. IE being integrated into the OS is one of these examples, but only one. When they moved IE into the operating system, they destabilized all of Windows. They have done this with many things. When you remove architectual barriers to subsystems, you do indeed speed things up, but you reduce stability by a much greater factor.

I totally agree that talking about any version of Windows from WinME backwards is beating a dead horse. Many of the problems with WinXP are driven by marketing decisions Microsoft made. Such as -- as you said -- running as root most of the time so Windows would be easier to manager for the typical user.

I am surprised that still, after all these years, that Windows has not seen the solution that UNIX (and probably many OS's) takes to DLL Hell -- use versioned DLL files so something linked against an old DLL will use the old one while something linked against the new one will use the new one. Viola. Problem solved.