First, those deals that are too good to be true? Many of them are too good to be true. If you are the first person in line at 4 AM you may get the one ultra-low price laptop that a store will have in stock. But, if you're a 'late' riser, who doesn't make it to the store until 4:05, you can forget about the miracle-priced computer.
Other computers may also be on sale at insane prices, but take a careful look at exactly what it is that you're buying. I've seen several netbooks deals that sound great... until I looked closer and saw that they require pricey, two-year mobile phone contracts on top of the up-front price.
I'm not saying you can't get a good deal. You can. Just don't get too worked up about sub-$100 priced computers, or you may end up disappointed or with a PC that costs you far more in the long-run.
Before setting your alarm clock for 3 in the morning, you also should keep in mind that many vendors are offering the same deals at their online stores. Given a choice between standing in a crowd at your local Best Buy and sitting at my computer and shopping, I'm at home at my PC every time.
Before you start shopping though, here are some specifics to keep in mind.
If you're going to buy a new Windows 7 PC, be sure to get one with at least 2GBs of RAM, and if you can get more RAM so much the better. I've found adding RAM to a computer usually gets you the most bang for the buck from any upgrade. Avoid netbooks with Windows 7. Windows 7 Starter Edition may, in theory, run on 1 GB of RAM, but it's no fun and it lacks many of Windows 7's best features.
The version of Windows 7 that you'll want to buy for a home PC, by the by, is Windows 7 Home Premium. Windows 7 Ultimate is also worth buying if it won't cost you much more. On the other hand, you want to avoid Windows 7 Home Basic. It has more features than Starter Edition, but it lacks such basics as the ability to play DVDs. If you buy a 'deal' with Windows 7 Home Basic, it's a deal you'll regret.
If you've been lusting for a Mac, now, or rather tomorrow, November 27th, is the time to buy. Apple will offer modest, about 8% sales on Macs on that day only. Still, since Apple almost never discounts Macs, it's still better than nothing. Other vendors, like MacMall, will also offer lower Mac prices for longer periods of time. For what it's worth, I think the Mac Mini, which will also be on sale, has always offered a great Mac at a PC price.
As for Linux, there's not a lot to pick from, I had one deal I liked a lot, a Dell's Vostro A90 Netbook for $184. This is a nice netbook that comes with Ubuntu Linux, but it appears that they're already sold out. Sigh.
Still, any netbook you can find will run desktop Linux successfully, so if you're heart is set on Linux, shop around. Even the most minimal-equipped netbook will still do well with Linux running on it.
Good luck with your shopping!