Are you saying your looking for files older than that of the date in which the computer was built with OS install date?
In my picture attached below this HP Windows 7 based computer was purchased and built in 2015 and it has system files that are dated 2009. So you will need an exclusion list in order to keep out system files that I am guessing you dont want to target?
Do you have a specific folder or directory you want to target to complete this action or just run across the entire C: drive etc?
Also... there is a cool program I use called XXCOPY that has an "older than" option which xcopy doesnt have with:
/DB:<date> Copies files that were changed on or before the specified date.
So if your trying to hunt down some old files that were 1-1-1980 you should be able to find them with the /DB:<date> switch option of xxcopy in which they would be copied to a target location that you specify. The <date> replaced with a date that can be any date you want as a starting point. SYSTEM DATE though is tricky because SYSTEM DATE will be the date in which this is run in which everything would be older than when this is run. So if system was built say in 2015 you can use a date for mm/dd/yyyy for sometime in 2015 or if you have an idea of how old the files are such as they are of the year 1980, you can specify a date in 1981 and not get anything newer than that date in 1981 etc.
More here on XXCOPY:
http://www.xxcopy.com/xxcopy01.htm[attachment deleted by admin to conserve space]