It depends on how you want to do it. There is a very good how to here
http://wiki.maemo.org/Updating_the_firmware

Basically you can update the firmware yourself using a PC and usb cable. Lots of people on here do it quite regular so there is minimal risk.
Be sure to read the wiki right through and follow all the instructions to the letter.
It looks daunting but if you break it down into steps it is relatively straight forward and takes around 15mins.