[Update: 11/29 - I'm starting to get the annual influx of questions about how best to buy a computer for the holidays so it's time to refresh and repost this guide. Enjoy!]

If you are going to buy a PC, here's how to do it. (If you're going to buy a new Mac, you have a dizzying array of one choice).

First : buy a Dell.
Are they the only game in town? No. But if you want the best computer, for the best price, with the best support, go Dell. Are they perfect? Nope. But honestly, it's as good as you're going to get.  Trust me on this. I've unofficially ( and begrudgingly I might add :P ) supported the computers of everyone I know for the last 10 years and anything but Dell is a nightmare. Just go Dell.

Oh, and buy it online, you won't get the same deals over the phone.

Second: Buy near the end of a fiscal quarter.
About 3 weeks before the end of a quarter, Dell is trying to reach revenue goals and they start deeply slashing prices. So, Jan, April, July, Oct.

Third: Don't shop on Dell.com, use the "deal" sites to shop. (Then of course you'll buy on Dell.com.)
My favorites for watching computer prices are:
SlickDeals.net (**)
Rage3D (these guys have Dell deals almost daily, SlickDeals gives you only the best ones).
CSB (Watch this page in particular for good Dell deals) has gotten progressively better over the last few months. A great Dell watcher, complete with good coupon codes.
These sites will show you the formula to follow when ordering to get the very best deal. Usually a combination of the right components, and some discount/coupon code(s).

Fourth: Find the sweet spot.
You should be able to get an excellent computer (without monitor) at any given time for well under $500, with no trouble. The trick is to get just a step or 2 under the newest technology, particularly the processor (CPU). SlickDeals, etc will do this work for you, so don't sweat it too much, but just know that if the best processor out there is 3.4Ghz, you want somewhere south of 3.0 (and this difference is not noticeable, but makes a HUGE difference in price).

Fifth: Stick to buying a computer every time the speed of processor double.
In other words, if you have a 2.0GHz machine, you'll buy when the sweet spot hits 4.0 Ghz. This is a good idea for a couple of reasons. First: Buying more often than that makes your ROI lower. Small changes in computing speed are hard to detect. If you are really hurting for some more power/speed -- upgrade your RAM, it's cheap and gives you the best bang for the buck. Second: Buying this often keeps your computer from being obsolete and makes it a whole lot easier on the (ahem) "computery guy" in your family that is always keeping you in shape. Older computers stop working with new software, they fall apart, they have mystery problems, they become a waste of time and money, and springing $500 for a new one is much cheaper and quicker. Yes... computers are sort of disposable. Sorry.

Good luck!

(**) This site is a daily visit anyway, it's a fantastic site where I've learned about and bought thousands of dollars worth of stuff. Most recently I picked up 9 Game Cube games for $5/ea after learning about it on SlickDeals. I've picked up some insane deals from there. If you don't already know about them, you'll be thanking me.

If you don't want to suffer the download.

As promised, here a great example of what you can get from Dell if you play it right. If you have the technical sophistication to make this work (i.e. installing your own OS) then this deal simply can't be beat. A monster machine, for $394.

This deal from yesterday and this one from last week (both now expired) are other nice examples that included LCD monitors.

Note these usually expire quick, so if you see a good deal you want, hook it up ASAP.

Looks like 2.8Ghz is the sweet spot CPU speed FWIW.

Microsoft has revised its plans to deliver Windows XP SP2 through the Automatic Updates (AU) delivery mechanism in Windows to give customers more time to plan the rollout of this critical update, or temporarily block the download of Windows XP SP2 to those machines using AU.

Here is the revised delivery schedule of Windows XP SP2:

8/16 - Release to Software Update Services.
8/18 - Release to Automatic Update for users running Windows XP Home Edition only.
8/25 - Release to Automatic Update for all Windows XP users including those running Windows XP Professional Edition; release to Windows Update for interactive user installations.

Lavasoft has released the newest version of their anti-spamware tool Ad-Aware, dubbed Ad-Aware SE.

This is a great little tool if you are trying to create an SPF file for your server(s). And if you send to an email list, you need to create an SPF file.

What's SPF?
In a nutshell... it's another step toward fighting spam. It makes it so spammers can't send spam, pretending to be you (or anyone but themselves). If this catches on (and it is catching on--MSN and AOL already use it) then all email messages will have to accurately report their origins, which addresses one of the main deceptive practices of spammers and severely cripples them. SPF FAQ.

Microsoft bought this great little tool for making Outlook search actually work... well, and fast.

Now they are giving it away for free. Grab it.

Another Ra-Ra FireFox article. To which I respond: yup.

Here's someone who had less impressive results. Some silly testing and conclusions, but ok.

Luke Hutterman of SharpReader fame had these negative experiences

I should note that I'm not 100% pleased with it. It still has some trouble interpreting links, and a few other quirks... but I'm more pleased with it than I am IE. By a long shot actually.

A nice compliment to my own guide, Microsoft has this helpful, if inferior advice about spam.

Fighting unwanted e-mail (spam)

Handling unwanted e-mail (spam)

There's actually some great advice in there.

I haven't used it, and it looks like it might require a little technical sophistication, but I've heard good things about it. SpamPal. The price is right (free).