1. A user-customized installation system for software packages, comprising: a computer; a set of available software packages available on the computer; a selector to select a subset of the set of available software packages, the selected subset including at least a first package, a second package, and a third package and omitting a non-included package; a database including an indication that the first package and the second package do not conflict at run-time, a second indication that the first package and the third package conflict at run time and a third indication that the first package and a fourth package do not conflict at run-time; a validator to validate that the first package and the second package do not conflict at run-time using the database; an assembler to remove the third package from the selected subset of the set of available software packages and include the fourth package in the selected subset of the set of available software packages; an installation builder on the computer to build the user-customized installation including the selected subset of the set of available software packages, the user-customized installation to install the selected subset of the available software packages on a machine of the user; an update to a package in the user-customized installation, the update to the package in the user-customized installation becoming available after the user-customized installation was built by the installation builder; a notifier so that the user-customized installation system can notify the user of the update without the machine of the user checking whether the update exists; and an installer to install the update on the machine of the user after the installation of the user-customized installation on the machine of the user; where the update to the package in the user-customized installation can become available either before or after the installation of the user-customized installation on the machine of the user.