Yes, you have a MKIV navigation computer. One key piece of information you did not provide is the year of your car and if it is still under any kind of warranty. If it is under warranty, you can probably pursuade the dealer to update your nav OS for no cost. Though, that depends a lot on your dealer. It really costs them nothing to do the update (6 minutes).
1. You can do the nav OS update yourself very easily. Don't buy anything from eBay-- that is a total ripoff. The first post in the following thread has a link where you can download the OS update image. Uncompress the image and burn it to a CD-R using something like ImgBurn. If you search this form (and read through this thread too), you will find several posts that talk about how to burn an OS update disk and how to do the update. Basically, you just put the disk in the nav computer and wait about 6 minutes. Then you are done. It will give you status on the screen.
http://www.xoutpost.com/navigation-sy...available.html
2. The update does not give you new maps. It fixes some bugs and gives you new features in the nav system. I can not remember all the changes, but this thread might help some, particularly if you download and read a few of the TSB documents referenced. Some of the key features in later versions are Sirius support and 3-D perspective mode.
http://www.xoutpost.com/articles/all-...ystem-faq.html
3. The current highest MKIV OS available is version 4-1/91. That is available on the V29.1 OS release CD or the V30 OS release CD.