Question regarding proposed trip

First, there is no such thing as Eurail. Do you mean that you are using an Eurail pass? Eurail is basically a travel agency selling rail passes. If in Italy you will use trenitalia, the national rail road of Italy. The train between Florence-Salzburg is like most trains. The newer, higher speed trains are more comfortable and the slower, Regional trains are less so. And be sure you need a rail pass since most rail passes in Italy are not cost effective unless doing a lot of long distance trains. The supplemental costs for reservations can add up. Second, what to you mean by problems or reference to problem between the train companies. I am not aware of any problems, Most of Rome as does most of Europe will shut down on Christmas eve and remain closed on Christmas day. A few, generally hotel related, restaurants will be open for the tourists.

This first hand account may help you make a decision. Personally, I love Europe at Christmas time.
http://www.travelandleisure.com/articles/roman-holiday-2007

You should have no problem taking a train from Salzburg to Florence. You'll probably go south to Innsbruck, where you'll transfer to another train for the trip through the Brenner Pass into Northern Italy. Check RailEurope.com to see if they have the schedules posted. Of course, all train schedules and fares are subject to change with so many months before you go. It'll give you an idea what to expect.

The problem with using RailEurope is that their schedule only show some of the trains, the trains for which they sell tickets, not all of them. You want a complete schedule. For that you need the German Rail (Bahn) website. But German Rail won't usually sell tickets or show prices for rail travel segments entirely outside Germany. For that you need to go to Austrian Rail, www.oebb.at. Neither German or Austrian Rail will sell you a ticket online all the way to Rome, because in include a segment entirely in Italy, Verona or Bologna to Florence. For that you would have to buy a separate ticket from Italian Rail, either online or at the station. Austrian Rail will sell you a ticket from Salzburg to either Verona or Bologna (however far the EC over Brenner Pass goes, usually to Verona). It consist of two trains, an Austrian Rail train (RailJet of InterCity) that goes through Germany without stops from Salzburg to Kufstein, Austria, where you change to the EuroCity train from Munich to Italy. With advance purchase, you can get that ticket for a discount; looks like they start at €39/p. German Rail will not sell you a complete ticket from Salzburg to Verona, because both ends of the journey are outside Germany, but Freilassing is just across the river from Salzburg, a few minutes and a couple of Euro fare. You can book Freilassing to Verona (RE to Rosenheim, where you change to the EC) with a discount fare as low as €39/p.

Andy, check RoninRome.com - he's got info on Christmas in Rome. In fact, after looking at his article, I'm planning on going next year.

Thanks guys for the information. I read the xmas articles on Rome and all looks ok. I looked at the trains and there is a connection from Florence (11am) going to Kurfstein - then to Salzburg (7pm).