you can safely install them by making sure the system has an IOS that will accept trucha signed content and installing them with the installer for them. they do not touch any critical system software and are therefore not risky to install. I advise that you install one using IOS 37+60 and the other as IOS 36+38 (I may be wrong with the numbers on the second one but it should be close to that.) The different install versions offer different bennefits depending on the IOS's they are based on. for example any installed with IOS 60 should be SDHC compatible.