I save my pictures as JPEG's ... I don't have an external HD [yet], so all the space on my MacBook is super precious As much as I love RAW files, they are huge! It couldn't hurt to keep both the RAW +JPEG files on hand, but if you want, I'd imagine saving the RAW files should be fine, as you can always convert them to JPEGS later down the line.
I save all RAW. I use Lightroom to process RAW into JPGs and have any JPGs automatically placed into a subfolder of the parent directory called "developed". Each time I dump photos from my camera I dump them into a folder titled this way:
Chotos2009(2009-12-08) Crazy Weekend
I have everything backed up via the www.mozy.com service. This way, even if my house burns down, I will have all my photos.