long term corporate bonds

recently i have found some bonds from some good companies (i.e. companies that unlikely file bankruptcy in the foreseeable future) have some bonds availiable for a nice return. Wonder if i should try some of these. Example,

1. 211327AB7 from Continental Corp pays 8.375% trading at about $90 yielding over 12%, maturity 8/15/12. I am sure Continental Corp. can survive 3.5 years. Moody/S&P rating Baa3/BBB-
2. 316773CH1 from Fifth Third Bank pays 8.25% trading at around $65 yielding over 12.5%. well this one has the maturity in 30 years. rating Baa2/BBB+
3. 984119AC1 from Xerox pays 8% trading at about $70 yielding over 10%. it has two callable dates at or above par. not sure which bonds will be called and which won't. maturity in 18 years. rating Baa3/BB+
4. 925524AH3 from Viacom pays 7.875% trading $66 yeilding over 12%. maturity in 21 years. Baa3/BBB
5. 260543BJ1 from Dow Chemical pays 7.375% trading $70 yeilding near 11%, maturity in 20 years. Baa1/BB-