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You can download trial versions of Noise Ninja, Neat Image, Noiseware and try them for free.  I personally prefer Neat Image Pro.  It lets you select an area in your image (for example, blue sky where you normally have a lot of noise) and then it creates an automatic setting for that image.  You can either select default, which is what I normally do, setting to remove noise or fine tune it more.  The program works as Photoshop Plug In or as Stand Alone, so you should not worry so much about your Photoshop Version.  You can also try Photoshop CS2 for free for one month if you go to Adobe´s site.  There are lot´s of programs out there and the top three listed above all do a fine job.  But it´s a matter of personal choice.  Just download the three trial versions, play around with them, and see which one you like the most.  I think that Noiseware is the easiest to use, but you don´t always get the best results.  You should not worry about SS noise rejections so much.  They are obsessed about it.  I think if they see a photo with blue sky or some shadows they will almost automatically reject it for noise despite the ISO setting.  SS´s working definition of noise is not a very good one.

Tried to post this last night but the new look seemed to prevent me logging in until now. 

My vote is for Neat image the free version is good and the paid versions are better, can queue images save filtered images as TIff or JPEG 12 and PS plug ins for the pro versions.

Over filtering can be a problem I usually just filter the sky one method I adapted from a lost source is listed on this page you have to scroll down.

I won't join the arguement whether to filter first or last just as long as you do it at some point.

A good idea to check your cameras settings my Canon 350D default setting is iso400 ouch iso100 is more sensible for normal daylight conditions.
 

I think this is a good review of these kinf of software http://www.michaelalmond.com/Articles/noise.htm
maybe a bit old but complete

my personal opinion, neat image + camera profile is the best choice considering quality of output and time of processing