OK - I use
 Code:
If TimeDiff(GetFileTime($File1), GetFileTime('file2'), 'd') > 1
  Delete $File1
EndIf

This will return a value showing the difference (in days) between the two files. If the value is 1 or more, file1 is older than file2 and can be deleted/copied/whatever.
 Code:
If TimeDiff(GetFileTime($File1), 'Today' 'd') > 90
  Delete $File1
EndIf

to delete files older than 90 days from today.

TimeDiff supports a MS flag, providing values between two dates with millisecond accuracy.

Glenn
_________________________
Actually I am a Rocket Scientist! \:D