Honestly, I do think for a lot of users FireFox or Opera is a much better alternative to IE. IE really is a security mess for an uneducated user, which believe it or not, most computer users fall into that group.
Now I cannot speak to IE7, as I have not used it or installed it, but I can only hope they made improvements. Outside of not trusting IE6, i think really everything comes down to personal preference. I have been using Mozilla Suite/phoenix/firebird/firefox for approx. 5 or 6 years, so I don't feel like switching anytime soon, but thats just personal pref.