Microsoft has just updated the following KB Article:
Configuration Manager client update is not installed successfully on Windows XP or Windows Server 2003 clients
Symptoms:
You install an update to any version of Microsoft System Center 2012 Configuration Manager or System Center Configuration Manager 2007 Service Pack 2 (SP2) sites. However, you can’t successfully deploy the update to Windows XP-based or Windows Server 2003-based client computers. When this problem occurs, the following event is recorded in the Windows installer log:
Action start 15:34:27: CcmCheckFreeDiskSpace.MSI (s) (B8:A8) [15:34:27:809]: Product: Configuration Manager Client -- There is not enough available disk space on to complete this operation. Installation requires at least 90MB free disk space.
Note This specific problem occurs only when the Configuration Manager client is installed on a nonsystem partition. For example, the Windows system is installed on partition C and you install the Configuration Manager client on partition D. This issue occurs even if sufficient free disk space exists on the partition on which the Configuration Manager client is installed.
This problem occurs only on Windows XP-based and Windows Server 2003-based clients.
Full details at:
http://support.microsoft.com/kb/2923401