How do you set grey card WB in photoshop CS2?

[Big Mike]

If I purchase lightroom 3 do I still need to use CS2?...
Does Lightroom offer same features as CS2 in the way of adjusting curves, levels, hues, saturation, converting to B&W, etc...
Does Lightroom 3 allow for "Action" downloads and use like CS2?

Thanks

Lightroom is not really an 'image editing' program like Photoshop is. Many photographers find that they use Photo A LOT less, when they start using Lightroom, but most still need Photoshop (or other image editing software).
Yes, in Lightroom you can adjust curves, levels, saturation and all the global adjustments. The current version of LR will even have some things that your old version of Photoshop doesn't, like clarity.
Lightroom doesn't have the ability to use layers, like Photoshop does. But it does have tools to selectively edit parts of the image (not just global adjustments). These tools include the adjustment brush and gradient filter.
Photoshop has actions, which are a string of commands recorded, to be played back. Lightroom works differently in that the order of 'commands' doesn't matter, so it saves the 'position of all the sliders' (for lack of a better term)....and it's called a 'Preset' instead of an action. And yes, you can save your own presets or download ones that others have made.

Lightroom is also a very good for browsing & organizing your photos. It was designed to make a photographers workflow easier and more efficient. Photoshop is an amazing program, but it's also a huge program that more features that any one person is going to use.

You can download a 30-day free trial, and if you do that, I'd highly suggest putting in some time to really learn how to use it, as it's not as intuitive to most people, at first anyway.