Why do my photos with my new cannon 7D have so much noise

Question

Hi,
We just got a new cannon 7D last week and took it on vacation.  When we downloaded pictures, they have much worse noise especially at low light that our old outdated rebel xt.  The pictures look ok at regular magnification, but when zoomed in they look terrible. I did not get noise anything like this with my xt.  I downloaded some as raw and some as dng and they look the same.  Even shots at 100 iso were quite noisy at 1/3 second.  We enlarge these and put them in a gallery and I suspect they will look very amateur.  I called cannon & they said to use their software to download the pictures, and that this image sensor is more sensitive so might pick up more noise.  I've downloaded thousands of pics with lightroom previously, so I don't think that's it & I know the image sensor is more sensitive, but everything I've read clearly says the 7D is a good camera and should have less noise than my old xt.  These are all tripod shots, mostly 100 iso & anywhere from fast shots (which are better) to long exposures in low light, downloaded to lightroom 4. 
Has anyone seen this?  I have seen some posts about high noise with 7d at low iso speeds.
Thanks

Answer 1

     Ok, I've tried to attach some photos without luck.  I went to that adobe.com website to make a link like the help section said, but it says the site is under repair.  Is there an easer way? I couldn't attach them by clicking the camera icon either. The help section says I can't attach a photo to a post for security reasons?    
     Anyway, my concern is that in the past with pictures that looked even a little noisy with my rebel xt, if I would try to print them at even 16x24 through a professional lab with a calibrated monitor I could definitely see noise on the prints.  I've gotten very good pictures with my rebel xt just by using a tripod and 100 iso with almost no noise, so it's hard to wrap my head around the fact that when I see alot of noise in a magnified picture that I won't see it on an enlarged print.  I do noise reduction in LR4, but it makes all the edges less sharp, so there is a trade off. My understanding is that you are supposed to zoom to 100% when doing noise reduction to see the effect.  I feel like I should have to do much less noise reduction with a 7D than a rebel XT.
Thanks for all your input