Actually AVI can be almost anything, including uncompressed (but I don't think there is such a thing as RAW format in video). AVI is just a wrapper that windows uses for video files and can cover many codecs such as DV, MPEG4, DIVX, XVID, Indeo etc. Uncompressed does not have a codec (by definition) but AVI can still be used to hold uncompressed video.
If you can get the uncompressed files into your PC, most NLE software will be able to edit it, although your hard disk will need to be super fast if you want smooth playback, especially with high definition frame sizes.
If you have to CAPTURE the uncompressed video, you will need a suitable hardware interface to do so. For example, if you are shooting video with a Canon XL-H1 which has an SDI output, you could get an SDI interface for your PC that would allow you to capture the uncompressed video, assuming your hard disk system was fast enough.
For consumer videocams, there is really no way to get an uncompressed video signal, so for the vast majority of people with limited funds (AKA me!

), the DV or HDV output will have to be good enough.