Does your Nav computer have a DVD logo on it? If so, you need the BMW Europe High version of the DVD (Do NOT buy the Professional or Business). If there is no DVD logo, then you can only use CD's

If you do have a Mk4 DVD navicomp, you should upgrade your Nav OS to V29.1.

In August, BMW Dealers had an offer on whereby you could trade in your old DVD or CD map disc and get a new latest 2007-2 version for £99 - the offer may still be on and it is a good price for a new sealed version.

Beware, some Ebay sellers will try and sell you a copy DVD - look very carefully at the small print and don't necessarily rely just on the photo! Be warned!

PS. Welcome to the forum!