Info on Primavera Contractor

Has anyone on here used "Contractor"? Any thoughts or comparisons to Suretrak? I have used primarily P3, with some time in Suretrak. How do they compare? Is "Contractor" basically a new version of Suretrak? Will it work with XP, Vista, and Win7?

AFAIK, Contractor is basically P5/6 but limited to 500 tasks/activities.