The date and time is different in the Cmos than to Windows date and time. If you were to double click on the clock icon at the bottom of Windows desktop and set the date back say 10 days, java returns the date that is 10 days behind.
My educated guess is that Java wont be able to get the CMOS time. Java was made as a high level programming language and CMOS should be out of the scope of java (not 100% sure). If you wanted to do something like that i'd try to do it with C or something like that.