1. Was Highlight Tone Priority turned on?
2. Have you applied some sharpening without noise reduction? Try it with color NR=25.
The 7D's noise on pixel level with lower ISOs is quite higher than the 40D and a bit higher than the 50D, but it should not be striking with proper processing, and the higher pixel count should make up for that.
I found the RC version to be far better than the beta version WRT noise. When an image is well exposed (hugging the right side of the histogram), low ISO images seem to me to have rather low noise. However, depending on your previous camera, you may need to recognize that there are some fundamental differences in the way that an image from a full coverage sensor looks compared to those with tiny light gathering areas for each photodiode -- primarily, that you can now see stuff that was previously too small to be seen. After I quit trying to drive a square peg into a round hole by applying the exact same workflow to 7D RAW images and, instead, decided to see what works better for me, my results improved dramatically. The RC version also helped, but is not quite there. The beta profile for the 7D was pure crap and, instead, I created some profiles of my own with the help of the DNG Profile Editor and a Gretag Macbeth color checker which helped with some of the problems, but not all. If you find that you are needing to add a lot of exposure compensation in ACR/DNG/LR, that can possibly be the reason that you see a lot of noise -- noise that gets dredged up from the gloomy shadows to the light of day just plain looks ugly. I believe that there is still a deficiency in the RC version WRT the 7D that somehow results in the images appearing darker than the same images processed in DPP or compared to in-camera JPG images (the JPG embedded in the RAW images). I still slightly prefer my own profiles to the ones provided in the RC version for most of my images.