I think these improvments in Microsoft Internet Explorer are long overdue, and as far as rip-offs go KDE borrows ideas from Mac OS and Windows just as OpenOffice has copied stuff from MS Office, I don't see any problem here.
As far as memory useage goes IE 7 does a lot worse than FireFox, in this example with both browsers displaying the same page IE uses 48.86MB while FF uses 35.3MB but this is only a beta relese of IE so this might improve some what.
MS still is doing thier best to push thier own products to the front, I wonder if the MSN search bar will do anything to improve MSN's market share of the search engines.