I would assume it is .NET, because I installed it using the .NET CDs. Here are the references I have added to my application:
CRVsPackageLib
CrystalDecisions.CrystalReports.Engine
CrystalDecisions.ReportSource
CrystalDecisions.Shared
CrystalDecisions.Web

I don't know why this one didn't capitalize the C and D
crystaldecisions.windows.forms

CrystalEnterpriseLib
CrystalInfoStoreLib
CrystalKeyCodeLib
CrystalPluginMgrLib
CrystalReportPluginLib
KEYCODEV2Lib