organizing file with lightroom or silkypix picasa?

Using Lightroom does not force you to change your current storage scheme. It can use its own hierarchy for storing your photos, or simply keep track where you keep them on your own. There's really no downside to using Lightroom, and lots of upsides.

I recently started using Lightroom myself. All my files are still exactly where they were before, and importing them into Lightroom was as simple as telling Lightroom where they are. If I wanted, of course, I could have Lightroom move them or copy them to its own hierarchy, but it doesn't matter since everything's right there in Lightroom no matter what.