in three weeks my family is going to prague and we want to take the train to vienna. there is also a possibility that we might want to take a train ride from paris to brussels later on in our trip. what is the best way to purchase the train tickets? thanks.

There are usually three trains per day which are direct (requiring no changes) leaving about 6:30 AM; 10:30 AM, and around 2:30 PM; these take about four hours. Other trains require at least one change and take between 5-5.5 hours.

If you are going to be in Pargue for a couple of days prior to the planned trip IMO you would be better off, and find it cheaper, to buy the tickets once you get to Prague.

You can check schedules using the GermanRail site: http://reiseauskunft.bahn.de/bin/query.exe/en

Input Praha as the departure city and Wien as the destination.

You can also check the Paris-Brussels schedules on that same site; again I would advise waiting until you get to Paris to buy tickets although you may be able to use the SNCF site www.voyages-sncf.com or the thalys.com site to pre-purchase cheaper tickets (as oposed to waiting until you get to Paris).

That I know of there are no budget flights between Prague and Vienna but you could check schedules using the www.opodo.com or www.skyscanner.net sites.

From Prague to Vienna, it's quite easy to buy tickets once you're there, and won't cost any more. Paris to Brussels, I'm pretty sure it's cheaper to book ahead, though others here are more experts on it than I am.

You should be aware that train tickets and seat reservations are two separate things.

A ticket entitles you to ride any train between the two cities but does not guarantee you a specific or even any seat.

A seat reservation costs about 3Euro (or the local equivalent) and does just that, reserves a specific seat on a specific train for you.

If you buy tickets in advance I recommend you not lock yourself into one particular train. You can stop by the train station in Prague, or Paris at any time and reserve a seat once you're certain which train you want to take.

If I'm travelling alone, I never bother with a seat res., I just grab any open seat on the train, and there are always open seats. For a group of 3-4 you might want to reserve seats just so you can definitely sit together in the same 6 person compartment.

thanks so much. this alleviates some anxiety for me. i will purchase the train tix when we get to prague.

There are two train stations in Prague. One (Holesovice) is on the north side (right at the end of red subway line, easy 15min ride from downtown) and many trains depart from there. The other station is closer to the main tourist area. Just be sure you know which station the Vienna trains depart from. You can buy tickets at any station.

Vienna has several stations as well - not sure where the Prague trains arrive.

check www.bahn.de for timetables, and Intrepid1 says, be sure to take a train with 0 changes.