It's an easy mistake to make: confusing the cost of your computer with the value of your computing investment. Yet no matter how logical it seems, that's not where the real cost and value is.

Let's say that you have just purchased a shiny new laptop. You've paid the retailer a princely sum of $1,600 -- a mighty investment in your present and your future. If you keep the laptop running for four years, your average annual cost is $400.

But don't forget the software. You'll probably purchase an office suite (word processor, spreadsheet and other office-related applications), a photo or other media editor and anti-virus subscriptions.

Depending on your use, you'll also need applications that meet your needs at home or at the office. Perhaps that will set you back another $200 to $1,000 over the next year or two. Then your needs will change, and you'll need to invest another $200 to $1,000 for the following couple of years.

Already, your investment is double what you originally thought. But that's still the tip of the investment iceberg. Add a few more dollars for the inevitable service fee to fix a problem -- either software or hardware, or for the service plan so you can call your PC manufacturer or retailer at no additional charge. You might even need to call in the troops because you've caught a virus that has crippled your productivity.

But that's still not the bulk of your investment. It's the cost of your time. Many people don't include the cost of time when they determine their true costs. If you're a lawyer, public relations professional, salesperson or in any profession that is billable by the hour, you'll quickly feel the effects of this investment. But when you're on salary, it's a difficult calculation -- because you aren't reducing your real income.

Don't let that fool you. Each hour that you spend investing in your computer is an hour that you can't invest elsewhere -- in a second paycheck-producing job, working on your relationship with your spouse, children or significant other, or even just taking in a movie. Your time is a valuable commodity -- no matter what type of job you have. Time lost is time you never recover.

Start with your setup time. You'll change the display settings; add utilities, such as anti-spyware; and experiment with the new features. During the first week or two of ownership, you'll probably spend 10 or more hours in these little tasks -- even though many of them may take you only five minutes. If your time is worth $8 an hour, those 10 hours cost you $80 immediately. If your time is worth $100/hour, that's a cool $1,000. Most people will be somewhere in between. And that's only in the first few weeks. You'll be investing your time continuously over the next few years -- whether you take your own time or the time of your administrator or IT person. Your cost of hardware is dwarfed by the cost of your time.

Don't let my talk about cost of computing scare you from making that investment in a computer. It's still one of the best investments you can make in yourself, your business and your family. It can help you reach new heights of knowledge, productivity -- and even fun.

But don't be fooled by the cost of a cheap computer either -- because if the cheap computer requires you to take more of your time, you've defeated the purpose -- and the costs will eat you alive. I've done it both ways. Getting the right computer, in the long run, is less costly than getting the cheap computer.