Since you are only going between a few major cities in a small amt of time, I would say you should just buy point to point tickets instead of a railpass.
Amsterdam to Paris, you can take the Thalys train. It is the major fast train on this route. It takes about 4 hours, although apparently in December they will start going even faster where it is only 3h18 between Paris-Amsterdam! (it also has some lovely views of the Dutch and Belgian countryside as well).
see: www.thalys.com, I’d pick Nederlands-English, since you will be starting your trip in Amsterdam. You can either go ticketless or print a paper ticket at home. Right now for your date (Dec 29), they have a special promotion fare for 25 euros between Amsterdam-Paris. (the cheapest fair after that is 36 euros) I’d hop on this fast as those do not last long!

From Paris-London, you are correct, I would use a Eurostar ticket. These trains go through the Chunnel and take less than 2.5 hours between London and Paris. If you are a youth (under 26), and buy tickets pretty well in advance, you can get them for around $65.

Between Dublin and London, I think flying would be the easiest. You can get a budget flight on Ryanair or Easyjet. Otherwise, ferries are involved which I personally would avoid like the plague (seasickness sucks!).
From Dublin back to Amsterdam, a budget flight as well would be the best bet.

Thanks a bunch! I just needed another opinion. I researched tickets & prices for hours and it was just overwhelming! The specifics help alot, too! I hadn’t heard of Ryanair or Easyjet. I will definitely look into it.

Check this site for cheap flight options: http://www.skyscanne… Be sure to factor in fees for checking a bag, using the bathroom, breathing, or whatever else they may be charging for these days.

I would look for cheap flights to and from Ireland. www.whichbudget.com will show you which low fare airlines fly which routes. While you might find it cheaper to fly from Paris to London, Eurostar (the chunnel train) is so much faster and more convenient that I’d choose that unless the plane was much, much cheaper. Look for cheap leisure fares and other specials at www.eurostar.com

Thanks to those who have replied. The information & websites you’ve given me have helped alot! With this being my first trip to Europe, I must say that this website definitely helps you plan or atleast connects you to people that can help. Thanks again!