I have the remains of an '04 Langster. I've replaced everything but the frame and I won't even be riding that in 2006. I'd recommend replacing the wheels first, along with the BB. You can get any number of 102mm or 103mm BBs and keep your stock cranks for a little longer. (BTW Langster owners, when we'll admit to being Langster owners, report BB and wheel failure as the two chief complaints.)

If you're interested, I have a set of 105 cranks (in 175mm) and an Ultegra BB. Both with about 10 miles on them. They were on the Langster but the chainline was not great. (you have to move the chainring to the inside of the spider - semi-fugly at best.) If you want them, PM me and they're yours cheap. (I mean cheap. Very cheap.) I'll loan you the crank-puller and BB tool for installation too.

Rampant capitalism aside, I strongly advise you to replace your wheels instead. You won't regret it.

Thanks for reading, Mark.