I've fought this same battle for a few years. Originally I used Canons software to process RAWs, it was terrible and I needed an alternative.
I tried Pixmatic Raw Shooter when it was free and that worked ok for me, and ran in Wine with minimal issues.
I switched to Picasa when it became available for Linux and supported RAW. It had much better album management, but looking back, the photos it produced looked terrible.
Eventually I switched to Capture One's software. I had to pay money for it, but it worked and it worked pretty well.
Recently I'd been getting fed up with them, their website is terrible to try to get updates from and there's not really a good way to manage albums of photos.
I gave the Aperture demo a shot as I'd just recently gotten a Macbook Pro. I found it very hard to use. Stuff just wasn't intuitive, the interface was cluttered and confusing.
Somewhere along the line I'd tried Lightroom v1 and thought it was very good. I was going to purchase it when it came out officially. I stalled when it came out and waited too long and missed it at the $99 launch pricing. I never did end up buying it and went back to Capture One.
Recently Adobe started up the Lightroom 2 Beta, I'm in the extended beta which will function until it's officially released and I can say with absolute certainty that I will be purchasing this when it's done. Everything about it is miles better than everything else. The interface is easy to use, and easy to get out of your way when you want to concentrate on what the photo looks like. It's got all the tools I feel I need to make it a one stop shop from import to web/print. I can't say enough good stuff about Lightroom 2 to do it justice. I guess my suggestion is that if you're really serious at all about your photos, stop screwing around with trying to find something Open Source and get Lightroom.
Of course YMMV, and that's why there's a demo/beta. Good luck, and good shooting!