How do i put a border on a picture with photoshop? and How much better is Photoshop Cs3?

Another way to do this is to go to your Layers palette, double click on the Layer (not the thumbnail) to bring up Layer effects. On the left you will see a list of options. Double click on Stroke. Select Inside from the choices (outside, inside, center). Click on the rectangle showing color to bring up the color picker and choose a color. Adjust the size to your liking, then click okay. Since you've now applied an EFFECT to the layer, you can always delete it or change it later, rather than changing the pixels in the layer itself.

CS3 has more stuff in it (depending also on whether you get Standard or Extended). Some things have been improved, like Vanishing point. You can also set the interface up to use the new version or legacy (if you like your tools palette in 2 columns rather than 1 for example.) Also Image Ready has been rolled into Photoshop, it is no longer a stand alone companion application; animation is available within Photoshop.

Hope that helps!

Select your picture using the rectangular marquee or pressing CTRL+A, then go to Modify > Stroke and choose size, color etc.
In Position choose Inside.
It's a short time that I work with CS3: it's a bit faster and the work area is arranged a lot better than before.