I just installed Sonar Platinum on my system, and my V-Studio 700 works just fine.
I did have a problem with the Fantom synth not producing sound even though it loaded properly (and all my other synths worked just fine). The issue appears to be related to the Windows registry problem with the Fantom that sometimes happened with Sonar X3 (and other version), and I fixed it using a variation of the original registry patch.