The classical Nokia N95 (N95-1) just received a new firmware. The new firmware is version 31.0.017 and it should be available for most of the Product Codes already. If you want to hack your N95 don’t update, because this version is not hackable. If you don’t care about hacking your phone you can easily update via the Nokia Software Updater.
Symbian World recommends you to update your phone because firmware updates usually improve the performance and safety of your device.