I imagine it's very similar to updating an N80.
Here's some instructions for an N80 that I've used and pm'd people on here...
(the product code you'll need for an N73... well you'll have to search here for it)
I got my instructions from a thread on this site.
http://www.cliosport.net/forum/showt...0004&highlight
or check the last post on this page:
http://www.ipmart-forum.com/showthre...=135312&page=3
Have a look and see if you follow it.
or, follow my instructions but you'll need the clio link above for the locations of the files you'll need.
Basically, download NSS, install it. Download and install GSM magic.
Run NSS, Run GSM magic.
Click Enable on GSM Magic
Go back to NSS. Connect your phone to PC via the cable. Select PC Suite mode.
On the top right hand side of NSS click 'Scan for new devices'
Then on the left click 'Phone Info'
On the right hand side where it says Product code. Enter the relevant product code (you may have to click enable first - if not click if after entering code).
Click 'write' - further down.
With your phone still connected, close NSS and GSMm.
Go to the Nokia Service Updater by going to nokia.co.uk selecting support. selecting your phone then selecting 'phone software update'
You must have your charger plugged in but after this you should be fine.
It'll take a while but do not use the phone while it's doing it.
You can upgrade to latest N80 version on the Nokia site or if you use N80 internet edition product code it'll change your phone to that. You can do this even if you have a standard N80.
Product code you want is
N80 UK - 0529378
N80IE (Euro1 (same as UK)) - 0539363
If you upgrade to N80 you can further upgrade over WIFI if you have it at home. Menu>Connect.>Device Mgr.>Options>Check for updates.
With N80IE the NSU will put the very latest on.
All of this is at your own risk. It is easy if followed correctly but don't blame me if it goes wrong. It will invalidate your warranty changing product code.
Back up all your contacts and stuff to Memory card.
Chris.