I just wrestled with this when upgrading an eCommerce site last week. IE6 was giving me tons of grief, which made me start thinking, "Why am I still supporting that beast anyway? Isn’t it insecure as well as a pain in the arse for designers?" I considered showing a page to IE6 users telling them that they need to update already and giving them links to do so (Firefox, etc.), but in the end I was able to get my layout working acceptably with an IE6-specific stylesheet and I decided to give it a temporary stay of execution.
I don’t expect to keep doing that, however. Before the end of 2009 I will definitely stop testing on IE6 and possibly do a browser test to warn holdout users to shape up. IE6 usage is down to under 20% in the standard stats that I check, and it’s even less in all the sites that I actually manange:
http://www.w3schools.com/browsers/browsers_stats.asp
Who still uses IE6? I’d say it’s just people who don’t know better. Most have probably got an unlicensed copy of XP or 2000 and can’t upgrade to IE7, but they could install Firefox or Opera and probably would if they were told they ought to by someone they trust. I can’t imagine an corporate environment where they won’t let you install your own software and still use IE6, but if there is such a place they deserve to be punished for their sins.
I still feel obligated to make sure that our clients’ sites work for IE6 users, but about the time that IE8 is released I’m going to start using the logic that IE6 is actually dangerous as well as busted and we’re doing people a favor by warning them (it was released in 2001, after all, and IE7 has been out since 2005!).