My first DSLR was a DS which I purchased when it had already been out for about 1-2 years. It was at the end of it's production cycle when the K100/110's were coming out. I've used the DS for a good 2-3 years and only recently (a couple weeks ago) did I finally upgrade to the K20D. The DS is really a great all-around camera. I like the pentaprism, 11-point AF, and AA batteries (which can be a pro or con depending on how you look at it.) Ergonomics are great and it's simple to use. If you shoot RAW, you'll definitely get the most out of the camera.
Even with my new K20D, I still love using my DS and always bring it out as a second body. I'm going to keep it until it dies on me
Whichever camera you get your hands on, I would say stick with it, buy a couple starter consumer lenses then think about investing in high quality lenses (DA*, Limited, or some classic K-mount manual lenses) if you want to go a step further. Lenses will far outlast the camera and you'll get more enjoyment out of it IMO. That's why instead of upgrading my camera body I just kept saving and got better glass. I never thought I'd spend over a $1000 on a lens when I first started, but once you get a taste of high quality lenses, it's hard to resist
You can check out the link to my photoblog in my signature to view some of my galleries. 95% of the photos in there right now have been taken with the DS.