I have a lot of saved forum posts that contain tips I hope might prove of interest as they seem to be questions that occur often.
How can I see or extract the embeded JPEGs contained within Canon DSLR RAW files?
RAW files contain an embeded JPEG as well as the RAW data - this is used to show in the LCD and from which the histogram is generated. With the CR2 files from the 20D you get a 1.5MP JPEG image 1536 x 1024 pixels and the CRW files from the 300D contain a medium sized JPEG (2048 x 1360 px). For both files, I use the free application Irfan View. You need to also download and install all the additional plug-ins for it to work, but once you've done that, it works fabulously - I use it daily.
If you choose the appropriate size setting (i.e. to show the 1.5MP embeded preview and not to generate a full res 'as shot' image, which is MUCH slower), you can view the whole shoot as a slide show just as though you'd shot it as small JPEGs.
Once an image is on-screen in that way, you can save it from there if you choose, re-size it, copy it into another application etc. You can also batch save/resize/adjust the entire directory in about a second per image. I very often extract a 600px-ish wide preview JPEGs for client proofing. As I work with minimal in-camera Processing Parameters, I add saturation, sharpening etc. as I do that, so the images approximate finished JPEGs.
It's a tool I like very much and always the application I view RAW files in first - I use it for all my proofing and selecting, only opening a RAW developer to work on finished images. I often just use the embeded JPEG if I don't need much from the image. I've set mine up to display details about the image - such as file name - at the top of the sceen in preview mode, so I can easily jot which view it is down for later reference. I can highly recommend it.
Fast Stone Viewer also does a very similar job and Picasa does something similar too. All three are free or donation-ware.