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Even beyond that, with IE6 you can familiarize yourself with the effects of standards mode versus quirks mode and become conversant with how the various DTD's are treated, and in gerneal get on board with the web standards that are going to take us forward.
Also, especially if you use cookies or are involved in e-commerce, you'll want to be comfortable with IE6 security settings and P3P privacy policies.
IE 6 was introduced in October of 2001 - hardly the new guy on the block at this point! If the download is the issue, you can order a CD from MS (and it also contains earlier versions of the browser) for the cost of shipping. Pretty handy on a dial-up connection.
Have a hunt through a few magazine cover discs - IE6 is bound to be lurking on one of them, and probably IE6 sp1 as well (though you'll still need to go to Windows Update and download all the subsequent patches).