Buying a desktop computer?

Buy the biggest monitor you can afford.

After all, you don't surf the web by staring at the inside of your computer. A 17" LCD monitor should be your starting point.
If you have a larger budget, and aren't a heavy gamer, look into LCD monitors at 19" and larger. I remember marvelling at a 22" monitor used by the aerospace company my wife worked for back in 1991. It was worth more than my car at the time. These days, 17" LCDs, which have the same screen space as a 19" CRT, start for as little as $180. Buy the biggest monitor you can afford, your eyes will thank you for it.

What are you using your computer for?

Unless you're running the newest 3D games or doing intensive graphics work, you don't need the latest and greatest technology. Surfing the web, email, instant messaging, word processing, accounting and downloading digital camera images are the limit for the vast majority of users. The truth is, those applications will run well on the most inexpensive modern PC or Mac, with one caveat, make sure your machine has at least 512MB of memory (RAM) and plenty of hard drive space.

High-speed internet will make you a happier computer user.

The days of using a dial-up modem are long over.
There's no need to be sitting at your desk, tapping your feet while waiting for the latest pics from friends or family to finish downloading. In our neck of the woods, you can choose between Telus or Shaw for your high-speed access. Neither one will tie up your phone line, and both have cheaper bundle pricing if you use some of their other services. Stay away from their "Lite" services, they're just too slow.