How can I find out which softwareversion I have?  Can I upgrade or do I have to take the TV to the dealer? 

Press MENU -  navigate to OPTIONS - press 0 - 0 - GO.

Thanks, can I upgrade myself or do I need a freightcompany :-) to take my tv to the dealer?

The dealer can do it by laptop at your own home (can't do it yourself).

What are the latest version of software for the 7-40,

Mark 1, 2, 3, 4 or are they all the same?

MK I: 7.91 (6.33 if NOT HD-rady)

MK II: 7.91

MK III: 6.11 (Build 533)

MK IV: 6.11 (Build 533)

I have noe learned how to get up the service menu, but seem to have a problem with finding  where the software version is shown

The instructions are as above on the 2nd answer.  When you get to monitor press go again and the top press at monitor information, on the top line you will see AP SW, after the SW is the current version installed on the tv.

Does anybody know what the difference between 5.08 on a MK 3 and the current version 6.11.

To go to the customer sevice menu;

Highlight options then press RED then GO.

You may find this easier?