I am just coming back from a trip with my Garmin 670. As mentioned earlier, it worked perfectly in the USA.

But in England, it made serious mistakes (e.g. mistaking overlays for junctions). And, during the last days in Germany, it made again serious errors which caused considerable detours.

North America and Europe are structured differently. Obviously, Garmin is perfectly working in North America, but makes considerable errors in Europe. TomTom (I borrowed the TomTom from my parents) works better in Europe (although I heard that it is not as good as Garmin in North America).

I know from previous threads that American posters tend to praise their Garmins (it must be a matter of national pride) but soberly analyzed you will go better in Europe with a TomTom.

Make sure that you get the technology called SiRFstarII. The earlier electronics are nearly useless in city canyons. Note: some manufacturers are very cagey and don't reveal what they're using. Avoid them.

The Google G1 (see T-MobileG1.com) has a built-in GPS application (Google Mobile Maps) that should work fine using WiFi in European cities. You can also navigate with a cell network connection, but this costs more than most people are willing to pay.

We have used microsoft.com/autoroute maps downloaded into a hand-held Windows Mobile device running microsoft.com/pocketstreets with good results. AutoRoute also runs on our laptop for in-car use.

Are you sure that you really want to be driving in Paris and Rome because even the most seasoned drivers don't!

I'm pretty sure the OP wants a GPS to walk around Paris and Rome.

We used a Garmin in the French countryside last August/Sept. While it's not perfect, it was a huge help. However, we discovered while driving into Toulouse, that it doesn't "know" pedestrian areas as well as it should and as Robes said, it can lose the signal.

A confusing factor in Toulouse is that not all pedestrian streets are pedestrian the entire day. But, we found our hotel without too many wrong turns and then ditched the car in a cheap car park.

But, I'm with yk and others, old-fashioned I guess--there's nothing I like better than a good, detailed map of large city, figuring out the route I want to take and then (hopefully) only having to glance at it from time to time.

Everyone only has to look at me to know I'm a tourist, so consulting a map isn't really going to make much difference!

The Garmin Nuvi 670 is a discontinued product. The preloaded maps in the unit are from 2007. Before you purchase it, you should find out how much it'll cost you to get current maps. I've heard (like 4th hand info) that some people were successful in asking Garmin to give them the newest maps for free; but you should find out if that's really true.

But again, if you are only going to be walking around the city and NOT DRIVING, I suggest Streetwise maps.

The OP is a few years old now and a lot has changed in GPS, not to mention phones. Garmin has a wonderful product the CityXPlorer maps which are available for newer model 1200 and up units. These gps have an enhanced pedestrian mode which provides for directions on all modes of public transportation. You park your car, set the unit to pedestrian and put in your destination - now it tells you how to walk to the bus stop or metro station, which train to take and when it will arrive. It even knows about the last Metro in Paris and warns you about it . The best part is that the City Xplorers are cheap downloads of only the metropolitan area you need in Europe or North America. $10 to $20. This way you do not need the expensive full Europe or US maps. When you get back to your car - set the unit on car and you get full voice routing of all the roads in the Metro area for that City.