I have a Lowrance X 17 mounted on the boat when I bought both new in 2004. I bought a Navionics 2005 and works great. My question, will the 2010 navionics card download in my unit and what would the difference be in what I have now? Thanks for your response in advance.

Look on there website or call Navionics 508-273-2000. They say it shows on their website the details of the maps, but I coudln't find it, so I can't tell you where to look. It will work if the chip size is not bigger than what your unit can hold. I also have a 17M but don't recall what the limit is. I believe the unit limit is 1 or 1.5 GB. I believe the Gold series is like 2 or 3 GB and is over capacity and will not work but the premiums should work. The new chips will have more lakes and more of those lakes and the older ones will have 1' contour lines, I just don't know which ones they are. If you can't find it on the website call Navionics, they will be more than happy to help you out. They are not only the leader in navigational mapping, they are the leader in customer service. I am having issues with my unit but if you are wanting to know if a certain lake is on the 09' Premium South chip let me know and I can pull up the area and see if it's on there.