By Bill Rigby NEW YORK (Reuters) – Satya Nadella has enjoyed a fairly smooth ride in his first 100 days as Microsoft Corp chief executive, but he risks hitting a rough patch next week when he unveils the latest models of the tepidly received Surface tablet. Investors have lapped up Nadellas mobile first, cloud first strategy to recast the venerable software maker as a devices and services company, sending its shares up 9 percent since he took the helm. So far he has stressed the services side of the business, making the momentous move to put Microsofts Office suite on Apple Incs iPad. …