but are you telling me that there is no way that Microsoft could've came out with a version of IE 7 applicable to any of their other systems...it just wasn't possible...completely out of the question ?
That is exactally what I am saying. IE7 is going to include a number of system calls that signal the buffer checking from SP2/longhorn. to preform kernel level buffer checks, mem security handling, and so forth, it needs the SP2/longhorn core that win2k and lower will never ever ver be able to get without a complete software rewrite (XP?).

this isn't just another update to IE7. This is a recoding from the ground up of their IE software, with prevention methods for buffer overflows, activeX browser stealing, advanced pop-up detection, minor virus protection by protecting the IE7 system files and drivers. Something only the XP/longhorn core can do.

This is a LARGE step for IE, if you've read the dev blogs and current documentation of it. Not a simple "redo it for money", but a complete recoding for browser improvement. something... that no matter how you put it, the 2k and lower kernels could never handle.