Your Kryptonite U-lock is probably fine. As suggested by frankemike, if you're concerned, you might augment your U-lock with a second lock (there are reliable reports that by upping the 'fuss and bother' factor, two less secure locks provide more real-world deterrence than a single more secure lock.)
Use good locking technique! There are numerous websites that discuss good locking technique (here's
one.)
A bicycle left in a public area can't be made
theft proof, but even in high theft areas with experienced thieves, you can take solace in the knowledge that you don't have to outrun the bear, you only have to outrun your buddy.
