My PC date/time will not display the correct information?

Hi Folks now this is my problem the Clock on my PC will not keep the correct time I Have changed the battery I have sync'd it with the internet time and it still loses time. If I reset the time/date and sync with internet time the PC will lose up to 51 minutes in 3 hours if the PC goes into standby mode when restarted the time displayed is when it went in to standby if I shut down the PC the same thing applies ,, extra info you I upgraded from XP to Vista if I set the clock through the CMOS settings I get the problem as explained ,, if I reset the clock from the control panel link once the time/date has been corrected and resync with internet time I click on the ok (that works) the page disappears and on the remaining page the apply box is inactive but the ok tab works,,this also applies when I reset the clock by clicking on the time displayed in the bottom right corner,, so if anyone can help any info received will be more than welcome,, please reread the question before you reply as all the info on the problem and what I have tried is there maybe not best explained but your dealing with a bit of a PC dimwit so please keep it simple with any replies,, many thanks for reading regards to all Tony