Where to start when upgrading software (MKIII)

[e36]

Hey,

I just install a 16:9 full screen on my '01 X5. What a difference!

However, i want to tackle uprading my software. I thought about getting a MKIV navi, but putting down $800 right now is way too much. I've been trying to understand this whole "version" ordeal but its not completely clicking.

How can i upgrade my MKIII software? I have v17 right now. I am looking to upgrade higher (at lease to one with BMW welcome screen). v23 seems to be the most compatible now.

ANY comments, opinions, and tutorials woudl be very helpful.

thanks,

mike