Photoshop CS3 was the best out there, except for all the others.
Don't get me wrong it works, but it doesn't work well a lot of the time, screws up the alignment regularly, doesn't blend properly even more regularly and quite frankly was sub par to every program on the market that is actually dedicated to generating panoramas. I won't comment on CS4 I haven't tried it.
Here's a tutorial:
1. Download the trail of Autopano Pro 2.
2. Point it to the folder containing one or more of your shots that may line up.
3. Push the green button and watch it magically find all the pictures that are part of the panorama and align them for you.
4. On the list of panoramas that shows up on the right, either go in and start playing with them, or hit render.
I have never used a program that was so good, easy to use, and above all fast. The CUDA acceleration made a huge difference over previous versions, and when I simply pointed it at the folder of the Columbian ice fields I took at the start of the year, it successfully found every one of the 9 panoramas I took out of the folder of 400 images, including the 170mpx one.