I have been looking at the polish train site. I may be wrong but I do not think I can buy online. Is that correct? I want to go from Warsaw to Krakow on a weekday. One way only.
Do you think I can just buy my ticket at the staion or do I need to reserve beforehand. If so how do I reserve a ticket

I've never tried to buy a ticket online for trains in Poland, but I have bought them in person in Krakow and it was difficult. I don't speak Polish (and my French did me no good) and we were trying to buy tickets from Krakow to Vienna... no one working at the ticket counters spoke English (or French); however, my friend with whom I was traveling was fluent in Russian. Although the ticket agent was NOT excited or thrilled to speak Russian- she could, actually, in Krakow we found that most people over the age of 35 spoke Russian (left over from the USSR/Communist years). Because she spoke Russian, we were able to get our tickets. It may not be a problem now- we were there in 2003. Just be advised that you may want to have your destination, times, and one way written out in Polish so you can hand it to the ticket agent... have fun- Krakow is amazing.

I don't know about buying it on line. It should not be a problem buying it at the station. That is what the locals do.

However,print out the screen with the place you want to go and the times the train goes, and just point. That way you at least know of an alternate train if you happen to miss the one you want.

You might also want to check out the Austrian train site. You can use if for most of Europe. Just type in Warsaw to Krakow.

Oops sorry the web site for Austrian train
www.obb.at

No problem! Find the ticket hall at the Centralia (main)train station. Ticket windows are at one end, stairs to trains at the other end. Train times are posted above the ticket windows. Current travel information is posted above the steps.

Prosze bilet do KRAKOWA. Please a ticket to Cracow.
Drugiej klahsi? First Class
Pierwsza klasa? Second Class
Jedna strone. One way
Pospieszny Fast
Ekspresowy Express
Osobowy (avoid) Every stop

Przylot Arrival
Odlot Departure
This information is posted throughout the station. It also notes the departure platform.

Real rain information is posted at the platform. Passenger cars are marked 1 or 2. If you have a reserved seat. you need to find the correct car.

Bury your valuables...security has been improved but don't take any chances. Three or four man gangs operate. They have usually spotted their 'mark'. He/she will be sandwiched just after he/she enters the car. One behind and two forward. They attempt to pass the 'mark' and then do the pickpocket bit.

Yes, you can buy online at

https://bilet.intercity.pl/irez/

Thank you to everyone. These are good answers to my question.

Another note: It is possible to buy a ticket on the train. A fee is charged.

A few years ago I did reserve PKP tickets online via http://www.intercity.com.pl/

First I studied the online timetable, then emailed my request. In return I received an email reply (in English) with a reservation confirmation and number. I paid the conductor on the train after having showed him the email printout.

Every seat on that train was taken. In other words prior reservation had been a must.

some corrections to what GSteed posted:

Druga klasa (or drugiej klasy) - First Class

(Anything on Land)
Przyjazd Arrival
Odjazd Departure

(anything in Air)
Przylot Arrival
Odlot Departure

tor - track
peron - gate

Prosze napisz / Please write ...

I don't think you'll have any trouble buying that ticket in person, as there are so many trains on that route.

I have bought tickets in a Polish train station, and it wasn't too bad (but def. more difficult than it would be in Germany, UK, etc.) but I do know a little Polish, which I definitely had to use. I wasn't in Warsaw, though, but a smaller town, where the ticket clerks did not speak English (or French, which I also speak).

Buying tickets isn't that difficult, I just wrote the info on a piece of paper so there was no confusion -- ticket, one way, x to y, time (which I got from schedule).