compaq - I have found that night HDR is harder and you have to adjust the sliders in photomatix much more different than in the day. I could be wrong but I think the issue with night HDR is that when imported into photomatix it amplifies everything and you get that ugly look. Before you start adjusting.
Here are some suggestions. bring down your luminance to the left way low and bump up your lighting to the right. Also adjust blacks, shadows and gamma. I had a recent trip to the fair and took a lot of HDR shots and used 5 shots for some of my HDR's and it took me a while to get the settings just right. When I would import to photomatix it was pretty nasty looking. I could be wrong about this and maybe you might want to talk to janok as he seems to be very successful with night HDR.
here is s link to my images, once I got my settings correct, it was much better and that noise went a way. I could not use my original exposures because these were all hand held and they would not line up.
A very nice image Compaq. Try to go back to square one with the processing to battle the noise. Although, at web sizes it really isn't much of an issue. If you shot RAW, convert to JPEG first.