I made it just past 100K, but it really sucked when it finally went.
It was a Friday on my way to work, just before a holiday weekend. So this meant that no garage would even look at it, let alone fix it till Tuesday. I couldn't replace it while I was at work, and needed my car for Saturday AM.
I finally had to tow it to my mechanic (cost $80), and then have him replace it (additional unnecessay labor cost).
You can replace this on your own, and should probably do it as a precaution, because it sucks to be stuck and pay for it, especially if you need your car.
Its an easy project, and shouldn't take you too long. Plus, you can plan on it!