I've owned my current computer (a MacBook Pro) for almost three years. The 120 GB hard drive was nearly full, so I bought a 640 GB hard drive for about $120 and swapped it in. (It was pretty easy; I used the excellent instructions at iFixIt.com). My plan is to hang onto the computer for another two years before I replace it with a new one.

But when the time comes to pay for a new computer, where will the money come from? I might not have the $3000 I'll need, unless I start saving now. I decided to try out SmartyPig.com, a service that lets you transfer a set amount of money from your bank account every month (or other period you specify) into an online piggy bank. It's FDIC insured, and it pays 2.15% interest (up to $50,000, after which it drops to 1/2%). There are no hidden fees to use the service.

Once a month, SmartyPig is going to transfer $125 from my checking account into a piggy I've labeled "Computer." (It calculated how much I'd need to put away each month to meet my goal in two years.) When I've reached my goal I can either opt to have the money transferred back to my checking account, or I can have it sent to me in the form of a retail card (like Amazon.com) and receive up to a 12% "cash boost." Because Amazon sells Macintosh computers, I'll be able to use that to buy extra memory or other gear.

But the real savings I'll get from using SmartyPig is avoiding credit card interest charges. Using Credit.com's handy Credit Card Repayment Calculator I discovered that if I were to use a credit card with a 12% APR to buy a $3000 computer system and made the minimum monthly payment, I would pay $1846.64 in interest. Plus it would take me over 15 years to pay off the balance, which means I'd probably be paying for my nest computer and at least a couple of others at the same time.

SmartyPig is good for my well-being, too. It's more satisfying to set a financial goal and wait to buy something I want instead of charging it. When I pay for a big ticket item with money I've earned and saved, I'm more likely to appreciate it than I would if I buy it on credit.

I think I'll try using SmartyPig to start a vacation savings piggy and a new car piggy.

Mark Frauenfelder – Editor-in-chief of MAKE magazine and the founder of the popular Boing Boing weblog, Mark was an editor at Wired from 1993-1998 and is the founding editor of Wired Online.