Most efficient picture sorting method

Hi world4ch, as the title implies I'm having quite a bit of trouble sorting those 6000+ images I download from the internet.

Up until recently, all I could do was to organize my images in a hierarchical way, with a folder for each subject, and each image to its appropriate subject. The problem with that is that it's insanely long, crashes explorer (winXP), and really isn't practical at all.

Then I tried Picasa. The label system works great, I can apply multiple label  to each file, I can mark my ravorites with stars, but problems come when I want to continue assigning labels in another moment. Picasa shows the image both in the label and in the main folder! So when I come back at my computer, I can't come back to where I was and continue labelling my pictures.

So, world4ch, do you have a particular way of sorting a massive amount of image files with a multi-labelling system, for example a program that would act much like Picasa but that would give you the option to remove a picture  from the main folder once you've finished labelling it without removing it in its respective labels?

In the hopes to find an answer
-Anonymous gatherer of images that were neglected over the years

Wait... your explorer crashes when you view the directory with all the folders in it? WTF? Viewing folders, or files even, doesn't do that unless you're viewing them as thumbnails... but even still, having your actual folders show as thumbnails is ugly as fuck (it shows an example of 4 images on the icon) and you should just view them as icons, tiles, or anything else.