Ok,

• HIGH DVD's are for I-Bus (read older) Colour Screen Nav Systems, such as on the 3 series (E46), the 5 Series (E39), the older X5's, the X3's (E83), the Z4's etc.
• Professional DVD's are for MOST Bus vehicles (read new gen) such as the E90 (new 3 series) etc - with I-drive and I think the 1 series and probably the new 5 and X5
• Business DVD's are for the Monochrome in-radio type nav system where there is no map but voice instructions and arrows. These can be fitted in any of the vehicles that the HIGH type nav is fitted in but are easily spotted as there is no colour screen.

I think that covers it.

So, if you have an 'old' 5 series, with colour screen (4:3 or 16:9), with a Mk4 DVD based Nav computer (it MUST have the DVD logo on the front face otherwise it's a CD based Mk2/Mk3) then the HIGH dvd will be the one you need.

Some of the confusion lies in the fact that BMW called the Nav in the old i-bus vehicles 'BMW Professional Navigation System'. Confusing isn't it?