The update that I believe teeboz is referring to is for the Bluetooth/multimedia update available (normally) from the BMW update page. Normally you'd put your VIN into their site and they'd let you know if there was an update available for the system. in this case it wasn't giving him an option for his VIN.
I did this on my retrofitted iDrive back in February having got hold of another VIN that originally had iDrive, was the same year and had all the same spec as mine.
This is the iDrive software update page before I did the update...
And after...
It's straight forward, you simply download the update .bin file onto a blank USB stick from here... https://www.bmw.com/en/footer/software-updates.html
Then place the stick into the USB port in the center console (NOT the glovebox one!!).
Scroll down to Settings, then down to Software Update, then Update Software and it'll commence the update. Follow any instructions given on the screen.
To be honest you probably won't notice any difference at all

:driving: