The K100D is pretty full-featured, the main feature that it falls short on compared to other entry-level DSLRs (as well as the K10D) is its small buffer, that can only do 5 shots in one burst. The K10D on the other hand, can take them full-speed until your card fills up. This has never been an issue for me and I think it's unlikely to affect most shooters, unless you're a hardcore sports shooter.
Where I've found continuous shooting to be a big deal is "limited time" shooting opportunities. The first example that hit me was shooting a neighbor's daughter in a figure skating competition. She was only on the floor for a few minutes. She was spinning during a lot of that time, so I needed fire off several shots in hopes of getting a shot of her in a good orientation. I quickly filled my 9 shot buffer and spent the rest of the time squeezing out what few shots I could.
I found that I ran into the same problem any time I wanted to shoot something that was very time limited and had lots of shooting opportunities. With kids, those situations seemed to come up a lot. With my old camera, I had to reduce my shot rate to keep from hitting the buffer limit. It drove me insane to have the perfect shooting opportunity but be unable to shoot because the buffer was full.
Keep in mind that the buffer sizes Groucho posted above are JPG. I usually shoot RAW. In that case, it's 3 shots for the K100D vs 10 shots for the K10D. The shooting speed is also different (2.6fps vs 3.1fps). That's not a huge difference, but it could be useful if you shoot a lot of very fast motion (golf swings, divers, runners, etc.).
It may seem crazy to fill a 4 or 5 shot buffer in a couple of seconds and still want more if you come from a film or p&s background. Once you
can shoot that fast and it doesn't cost you anything, you might find a lot of opportunities to do so.
I'm not saying that you are making a bad choice either way. I just think that
you need to decide whether the differences are worth it to
you. It's obvious that they are not to some people here. For me, I'd get the K10D in a heartbeat over the K100D at even twice the price difference.
We all value things differently. That's why you can sleep at the All Star resort or the Grand Floridian. Everyone has a different view of what's important.