First consideration: If you're running Windows, you must have Internet Explorer installed. Quite a few things actually use it, where it's not obvious.

Second consideration: If you want to be safe, you have to keep your Internet Explorer up to date with security patches, whether you use it for web browsing or choose another browser.

Third consideration: If you keep both your Windows OS and IE up to date, most people don't have a lot of problems with IE.

As to the choice between IE6 or IE7, there's some advantage to the way some relatively new safety modules are incorporated in IE7, but most of those features can be added onto IE6 if you really want them there. There probably isn't a lot of difference in safety, for now, if your IE6 is current with available patches.

IE7 is sufficiently different that some "retraining" may be needed to find all the buttons, and learning how some of the new features work. You may, or may not, like it after you've given it a trial. It can be uninstalled to go back to IE6 if you choose to (but do ALWAYS use the Control Panel - Add Remove Programs to uninstall, if you do).

If you have problems with some kinds of "cranky hardware," sometimes including limited RAM, marginal processor, obsolete MB chipset, etc., or if you frequently visit sites where the sites are "less than fully compatible" with IE, you may find another browser accomodates the peculiarites of your setup and that makes the other browser more fun to use. You may also simply like another browser for the way it looks, feels, and strokes your tender pschotic ego psyche.

Do what makes you feel good.

John