I've checked out the 'Let's Exercise!' thread and more than once I felt like simultaneously crying and breaking my tablet when I compared myself to what those guys had done.
Don't worry, we all feel that way. The cool thing about being part of a community like this is that there are always fellow artists we can admire and envy, that way we find the motivation to push ourselves farther than we would have been able to do on our own.

Working digital in itself doesn't help you create better artwork, though if you learn it you'll eventually be able to create stuff faster than you would be able to if you stick to traditional. The general principles are the same though, and I encourage you to continue traditional drawing. I was actually talking to a friend about this just yesterday, and I encouraged him to draw more and to draw with a pen instead of a pencil. The pen has the great advantage of not being easy to erase, which will force you to draw with your mind instead of just with your hands.

If you want to learn digital you should check out the blog www.ctrlpaint.com