There never used to be an 'offical' Suunto USB cable that worked with the Vyper, the only USB cable available had a plug which fitted the wristwatches.
However, it does appear that Suunto now have one for the Vyper et al. (I think it might have been released along with the VyperII). It wont be cheap though.
You could also check out CustomIdeas Suunto USB Cable
One of my buddies has this, and finds it works well.
I keep meaning to get one myself so I can use it on my Mac's.