TRAINS in the Netherlands are fast, frequent, comfortable, punctual and cheap; well, they were until they got privatised, when their punctuality started to suffer. Many stations have a taxi-sharing scheme called "Train Taxis" which cost only €4.20: buy a Train Taxi ticket when you buy your train ticket.
You can buy tickets at machines, or at the ticket office, but at the ticket office they charge a 50 cent or €1 surcharge for regular tickets. There are two types of machine; one sort accepts cash and direct-credit bank cards (Maestro/Cirrus). but the other sort only accepts the bank cards.
You can look train times up online at the Dutch National Railways (NS) site, and it will give you times, platforms and prices, though to be perfectly honest the German Railways site is better for international travel.
There are direct trains to and from Belgium (Brussels 21⁄2 hours), France (e.g. Paris 4 hours), Germany (Cologne 21⁄2 hours, Berlin 6 hours), Switzerland (Zurich 8 hours), and with one change you can reach places like London (5 hours, via the Channel Tunnel), Copenhagen (11 hours, the train actually rolls onto a boat), Prague (11 hours) and Vienna (111⁄2 hours). Even Moscow is only 2 changes away (well OK, and 33 hours).
PLANES Schiphol airport is very close to Amsterdam centre. There are trains day and night, seven times an hour through the day, hourly in the dead of night, and which take about 15-20 minutes. A single journey costs €3.60.
Taxis take 10-15 minutes, though beware of travelling in the rush hour. Some taxis charge a fixed price of €35 to the airport rather than running the meter.
By the way, Schiphol has been voted the best airport in the world several times, and not without reason: the shops there are great, and of a wide range, from drink and chocolates to fashions and electronics. You might want to leave yourself some extra time for shopping. Don't necessarily expect bargains though; only the articles marked as "special offer" are truly likely to be cheaper than street prices.
There is also a small branch of the Rijksmuseum that is worth a visit (between the E and F piers, open 7-20, admission free.)
If you want to know what to take back for people, Dutch chocolate and cheese are very good (in fact Dutch Edam and Gouda taste nothing like the stuff bearing those names in other countries). There are nice stoneware bottles of Dutch gin (jenever) in two types Jong (young) which is the closest in taste to gin, and Oud (old), and there is Dutch Brandy (Vieux).
Schiphol's Duty-free Shops are online (go to the Schiphol site, and click 'Shopping'). You can even order online and pick your goods up when you leave (click on 'reservation service' after clicking 'Shopping').
Information thanks to Steven Pemberton's Internet Guide to Amsterdam