I also have Neat Image. There isn't really enough featureless area in the crop you have to "train" the noise filter properly, so I can't rework your image to show you, but I have found the software useful. Neat Image is a stand-alone piece of software unless you get one of the + versions (Home+ or Pro+) which also has a Photoshop-compatible plug-in. You don't need Photoshop to use the plug-in version; I have it the plug-in version installed on Corel Photo-Paint 12, Paint Shop Pro 9, and Irfanview.
I haven't tried Neat Image on any of my Canon 350D images, but here are some demo shots I have posted on Webshots. The shots were taken with my Nikon Coolpix 995.
ISO 400:
ISO 400 after denoising:
ISO 100:
It should be noticed that the vertical scratch on the sign toward the left of the image has lost some of its intermittent structure in the denoised ISO 400 shot that is visible at ISO 100. You can expect to lose some detail in low-contrast areas of your image along with the noise.
If you don't mind the graininess of the image but dislike the chroma noise, Neat Image allows you to remove noise from the chroma (Cr and Cb) channels only and to turn off the noise reduction in the brightness (Y) channel. Even the default setting deliberately leaves a little noise in the Y channel to keep the image from having too much of a "plastic" look.