Choosing the latest SMSMSE version

Currently running SMSMSE version 6.5.7.279 on Windows Server 2008 R2 with latest patches. Mail server is Exchange Server 2007 Standard. Hardware is Xeon 1.6GHz (2 CPUs), 12GB RAM, 60GB free storage.

I'd like to upgrade SMSMSE to the latest version. I see 2 newer versions available for download: v6.5.8.285 and v7.0.2.79. Which SMSMSE version works best for my environment?