I cannot recommend Norton's SystemWorks strongly enough. It finds and corrects problems before they happen, and helps you get things humming again if something bad happens anyway. It was logos who recommended this software to me, and it was the best $70 I've spent in some time.
For those of us who never turn off our computers, you can even schedule defrags of gigantic hard drives in the middle of the night when you're sleeping. The anti-virus software included is worth the price alone.
And it was Ron C. who recommended Norton System Works to me. However ...
ahem ... as I just learned last week, it doesn't stop a fractious printer from suddenly grabbing somewhere between 25 - 30 sheets of paper at once, cramming them into the printer drive, making horrendous noises, and then dying. At least, decent printers aren't all that expensive any more; picked up a Lexmark Z22 at Wal-Mart for $49.63, and got right back into business.
Of course, it was Sunday morning before church when all this happened ... but that's another story.