Find exchange 2010 version information
Find this in regedit:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\AE1D439464EB1B8488741FFA028E291C\Patches\DAB7360D98CBBF4498895E7EF3AFC452′
The key “DisplayName” gives the version (SP and rollup)
Example: Update Rollup 6 for Exchange Server 2010 Service Pack 2 (KB2746164) 14.2.342.3