Software Informer authoritativley advises that the latest version is 126.96.36.199, yet the download link leads to a microsoft page from which V4.5096.0 can be downloaded. Where is V188.8.131.52? or is there an error?
Apparently, Software Informer is not taking OS compatibility into account. 4.5 is the latest (maybe the last) version of ActiveSync for Windows XP SP2. The higher numbered (4.9, 6+) are embedded in (or updates for) Windows Vista.