A note to fellow authors:
I've noticed a few forum posts from potential buyers saying "I'm trying to find this song". They have downloaded the preview, probably several previews, and then have been lost in the sea of 100,000 tracks trying to find it again to purchase.
I place ID3 tags on my mp3 preview files and noticed they will remain on the downloaded preview. This way it can be easily linked back to your profile and you won't miss out on that sale. I'm sure it doesn't happen all the time but a couple of seconds to add your account name and the name of the track won't hurt.