Lets start with the over the internet help first.
PS7 required a Raw plug-in to look at raw files. CS2 will only support Adobe ACR 3.7 or below. It does not load 3.7 by default. You will have to download it from Adobe and install it. You can find it
HERE.
There have been several file readers created that will show thumbnails for Canon RAW files back as far as the 10D. I've had limited luck with them. Recently one was posted on this forum that allows you to see raw thumbnails in Vista.
Once you have the right ACR version installed, you should be able to see RAW thumbnails in Adobe Bridge.
Make sure you read the list of Camera bodies supported by the ACR version you download and install. If your camera body is not listed until version 4.0 or greater, you will need CS3 or LR to see your RAW files.