I converted my US 496 to the European version a while ago, and tried lots of things before finding out what really works. Even Garmin's Customer Support took months to find out that you actually NEED a memory card.
What I ended up doing to get it all to work was ordering a European City Navigator DVD and the biggest Garmin Memory Card I could get. I ordered it in the USA as the price difference to Europe was HUGE. I used TigerGPS, they shipped to Europe via UPS Express (still much cheaper and faster than buying it in Europe).
I also used MyGarmin to update the other stuff for like $35 each (Terrain, Obstacle, Jeppesen if I don't remember this wrong).
Again, this was for a 496 but I think the procedure will be pretty much the same.