Note that the following applies to and was tested on Altiris NS 6.0 SP3 R13, but may work with some adjustments on SMP 7.x as well (untested).
On some occasions, you may need to move the Altiris Agent on your Package Server from one drive to another, particularly if the first drive (probably C:) is out of space or was incorrectly installed to begin with. The following procedure will accomplish this, without having to re-replicate possibly dozens or hundreds of GB of packages (which is what will happen if you do this the traditional way of uninstalling/reinstalling core agent/reinstalling Package Server Agent).
How to move the Package Server from One Drive to Another (without re-replicating 10's of GB of Packages)
In some cases, the Altiris Agent and Package Server Agent may get installed to the C: drive instead of the usual D: drive (depending on the particular machine's configuration). ...