Why are government bonds attractive as part of a balanced investment portfolio? How does the tax treatment of certain types of government bonds affect their attractiveness to certain types of investors? What are the potential benefits / risks of investing in the following types of bonds in comparison to "standard" US Treasury debt of the 1 - 10 year variety (a) long dated zero coupon bonds (b) Bonds issued by a state or municipality with less than perfect credit (c) debt issued by a government agency like GNMA (d) CDO's which hold debt secured by such things as GNMA mortgages (e) inflation linked bonds?