Hmm I don't understand why so many vb.org people like IE, of course vbulletin's markup is a bit outdated (tables, tables and more tables for layout) so it might look ok in IE6, but still IE6 only causes layout (box model fail) and other problems. Of course IE7 is a lot better and I've heard IE8 is even better, good stuff, too bad about 70% are still using IE6..
edit: Yeah it's not 70%, I think
about 70% use IE in total, was mixing that up with IE6 usage, of course it depends a lot on your audience as well, but at
w3schools for example there's a 25% IE6 usage which is still quite a lot I think, considering it's a tech/web site.