Here are a few registry locations where you can look for XCOM entries. There can be a few more entries if you install in custom mode to use the SNA protocol.
HKEY_CURRENT_USER\Software\ComputerAssociates
HKEY_LOCAL_MACHINE\SOFTWARE\ComputerAssociates
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\XCOM Data Transport r12.0 SP00 (64-bit)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\XCOM Data Transport Maintenance r12.0 SP00 (64-bit)