Yes, I guess I will, because I just booted into the BIOS and found the hardware time off also. Cost isn't a factor,because I already have spares, it just that the battery position is such that changing the battery is something of a chore, and I'm a bit lazy. However I can't tolerate this for very long. It seems odd that syncing windows time would have any effect on the hardware clock. I had always thought it to only be the other way around.
EDIT: I just checked the date of purchase of the battery in use, and it was in April of this year, which means that it should be good for quite some time more. The expiry on the package is for 12-2020, so I would be surprised if the battery is failing, but who knows?