IE6 needs a win98 bottle, Office 2003 needs a win2000 bottle. Both work 100% in their own bottles though, and is the way they are intended to be run, that's exactly how I run it.
CrossOver will run those particular applications with much better performance, much lower memory needs, and no Windows code required (don't forget the price of a Windows license if you're comparing costs), so I'd not dream of running IE6 or Office 2000 under Fusion or Parallels... it's a whole lot of unnecessary overhead when CrossOver does those much, much better.
Obviously though, CrossOver's not a great general Windows application solution, as there are plenty of other Windows applications that don't work quite right under Crossover. That's where Fusion/Parallels really shine, outside of most games, they run a copy of real Windows on top of OS X, so almost everything works right.