Check the SET menu (ccfj1 described this procedure above) and in the right-upper corner you'll see figures like this SW 3-1/63. If the last figure is 63 - means that you have the latest navi soft.... if it less - might be there is a sence to update....

If you'll decide to update take into the account that MK3 is VERY sensitive to the navi soft - read carefully this forum regarding specific details for the soft for MK3