I know it's not an answer; but on IE6 the vast majority of the internet looks pretty bad these days.
Additionally, the kind of organisations that still run IE6 will probably also have super restrictive firewall policies that wouldn't let your site thru anyway.
Since high-profile sites like Youtube have officially discontinued support for IE6, I've been inclined to do the same; unless my client is will to pay a lot for that support!
On the other hand, I based my own site's theme entirely on the default TheThemeMachine and it looks almost identical in IE6 to other browsers.
Finally; Bertrand posted a theme switcher on his site that lets you change themes according to user agent string. So you could always build a really simple and plain theme to fall back to for IE6 users.