Last year my friend and I stood in line at best buy for 3 hours (which is not early enough for our area!!) and came out empty handed. While driving home we saw staples was open so we decided to give it a try. Keep in mind they were already open for 10 minutes by the time we got there.
It was great!! Got the 200gig Maxtor drive and a 512meg thumbdrive and was out of there in like an hour or so. Then I went over to the other staples and grabbed another thumbdrive. By 8 most of the items (hard drives, thumbdrive, other cheap hardware etc...) were gone, but some items weren't limited and thus you can get a rain check on them.:)
So I really think it is the area you are in will affect the lines. For us, our staples are not near any wal-marts, best buys or circuit cities. Thus I think that gave us an advantage as most people are stuck at Best Buy. The best thing you can do if you are doing this for the first time is to swing down there a few days before and ask the manager when a good time to swing down there is. This year I will be there about an hour before hand ,but that is only because I want time to swing by the other (less busy) store.:)