Sorry Alan, didn't mean to be flippant about it
The thing is that there are some fairly strong opinions here and these sorts of threads rapidly turn from a "pro's and con's" debate into slanging matches
The advice given above regarding trying both and then making your decision is fairly sound.
IE
can be a safe browser if (as already mentioned) you take the appropriate precautions, and are a little careful about what you download and what sites you visit.
I only made my mind up for certain after I had trialled Firefox for a while.
My IE was nicely secured and I never had any problems with it so that wasn't a contributing factor. In the end though I went for Firefox because I liked the interface, I like the tabbed browsing feature, and I like the whole look and feel of the product.
Sorry about my earlier comments, hopefully this is more useful to you?