If you like the security of government bonds, TreasuryDirect is the cheapest and easiest way to buy them.

It allows you to purchase a wide range of government debt, including Treasury notes, U.S. Savings Bonds and Treasury Inflation-Protected Securities (TIPS) online.

There's a $100 minimum investment for all types of Treasury securities -- bills, bonds, notes and TIPS -- and you must buy in multiples of $100. You can buy savings bonds -- which, unlike Treasury securities, are not transferable -- for as little as $25.

There's no charge to buy and sell through TreasuryDirect, which is open only to individual investors. A similar program, called Legacy Treasury Direct, is open to fiduciaries (trusts, estates etc.) and organizations as well as individuals. But only Treasury bills, notes and TIPS can be bought and sold through Legacy Treasury Direct, and there's a $100 annual fee for accounts totaling more than $100,000.

To open a TreasuryDirect account, you'll need a valid Social Security number, a driver's license number or state ID number, a U.S. address, a bank account to allow you to make electronic transfers, an e-mail address and an up-to-date Web browser. TreasuryDirect is all Web-based. A paper application is required to open a Legacy Treasury Direct account.

You can add to your investments whenever the type of debt you want is being sold. Short-term Treasury bills, for example, are available every week. Longer-term notes and bonds are auctioned monthly, quarterly or twice a year.

The purchase price is automatically deducted from your bank account and the interest you earn is automatically deposited.

The only real drawback to these accounts is that some types of investments can't be sold before they mature and there's a $45 fee to cash out the bonds the government allows you to sell.

How much will you make? Our CD calculator works for most types of government bonds, too.