Firefox...I have been using it for quite a while now and can absolutely say I love it. It's leaner, in my opinion faster than IE, more secure, and fully customizable. If you haven't been using the tabbed browser option in IE, I think you will love it in FF. I really like just having one browser application open and sitting in my task bar rather than one for every single web page I may have open at any given time. You can get it here
And once you have it downloaded, one add-on I would recommend (because try as you might, we can't 100% get away from IE) would be to download and install IE Tab. That one you can get here
. What this does is allow you to open web pages within FF that are better viewed (or may require) IE to work. Such as Windows Update. As far as I know, you have to use IE for that one, but it will work on IE Tab in FF.
A couple other add-ons I would recommend are Adblock Plus
, which is very useful, especially on this forum as it allows you to encode things (such as clickable URLs) within a post without you having to know the code. Adblock Plus is sorta self-explanatory. Killing a lot of the ads from showing up on a web page helps to speed things up, also. In addition to removing a big annoyance. Unless you like lots of ads on your web pages!
And there are tons of other add-ons available that you can spend hours going through. Installing is simple - just click Install on the page for the add-on, and another click on the next page that opens up, and FF does the rest for you.
As for completely uninstalling IE, I'm not sure you can do that in Vista, but if you install IE Tab, you still need to have IE installed in order for it to work. But, there aren't a lot of pages that I absolutely have to have open in IE in order to get them to work. I use it more at work because they have not fully endorsed FF and are optimizing very few of their web pages for it.