If you have your heart set on scanning, make sure that you try a few, and compare the image to a 500x500 that you can get from the internet. Do the comparison by looking at the screen in the applications you use most that will benefit from the higher resolution.
For Album Thumbnails, for example, I doubt there will be much a difference. For some full screen visualizations, the higher rez will probably help.
I think you may be underestimating the time needed for your project. One minute per Album seems too little. You have to scan, view, edit, name, associate, etc. I've scanned a few covers, and its a pain. I can't imagine scanning 500 covers.
Using either Amazon, Walmart or Google Images, I've been able to get most of my covers at 500x500, which I'm satisfied with. As an alternative you may want to get as many 500x500 as possible, then scan the remainder, which would reduce the time needed significantly.
The other factor, and it could just be my scanner, is that even though the resolution is higher, the image just doesn't look as good. Sharpness, color saturation, excess border and crookedness detract from the scan.
Good luck with whatever you decide to do.