I don't think it really matters what you use, as long as you try to keep your security as up to date as possible, as eventually even the "unhackable" gets attacked... You often see on many boards people arguing over what browser/OS is better than the other, but when it comes down to it, they are all much the same, so use whatever you feel happy with. I use Firefox and IE with outlook express for my emails and (touch wood) have never had a major problem in a long time (any I did have was caused by one of uncle bills magic "updates" As for migration tools, there are a few but as i never used any of them, I can't really endorse any of them, maybe somebody else can help there....
That's about it ... Firefox and Opera are the only 'real' alternative to IE ... 99% of the 'others' will be using IE own engine, they just stick some fancy do-da on the front.
If you have "corruptions" in both IE & Firefox I would be looking for the real cause.