Photo Management Software?

Hey folks,

Anyone out there have any recommendations for some good photo management software? I've got gigs and gigs of photos I've taken from my travels, yet right now I'm doing all the file management myself. Folders named by location, files batch-named by what they're pictures of. Here's where it begins to get tricky: in the interest of redundant safety nets, I've got *almost* all of my pictures both on my internal harddrive and on an external. However, for some groups of photos (especially trips when I shot entirely in RAW format, creating huge files), they reside solely on the external. I use a program to keep pretty much everything in the "My Docs" folder synced to the external, ignoring certain directories where these pics are stored.

I'd like to get into using something like Picasa to help me manage my photos, but I've got a few qualms with it. First, if I told it to scan both my internal and external harddrives for photos, will it think I have double the number of photos I actually have (aka, will it read photos from G drive and their duplicates on T drive and think they're different)? Second, I don't like the way that Picasa basically creates its own duplicates of all photos you choose to edit. I don't want that to happen - that's a huge waste of space, and I'm not working with unlimited amounts here.

Any ideas/suggestions? What do you guys use?