As I understand it, Microsoft has mucked around with the ActiveSync protocols several times, resulting in incompatibilities. In other words, typical Microsoft.
You may be able to access Windows Live directly using the vCal and vCard data formats. Most PDAs and many websites support them. That basically means writing your own sync protocol.
Although actually, in most cases, rather than making only a single app sync, you'd sync the entire device so that the data would go into the device's master database. For Windows devices, that would mean using an OS-level sync application.
An IDE is no substitute for an Intelligent Developer.