Hi,
catastrophic failure is rare. But you could get stranded. I've had that happen. Here's just a thought... Here's some NOS 105 7 speed hubs for 50 bucks.
http://sheldonbrown.com/harris/hubs.html
Here's the rims I got for my next wheels for about $60.
http://cgi.ebay.com/2-Black-Ambrosio...QQcmdZViewItem
You can have them built up into a nice new wheelset for under a couple hundred, and you don't have to do it all at once. You could buy the rims now, get the hubs later. You could also keep an eye on ebay for NOS hubs. I've gotten rims and hubs, so when one of my wheels dies, I just need to get it built up. That takes some of the sting out.