Hey Dan,
This functionality is native to GSS when using the built-in create/deploy image tasks. The way it works is that the default answer file on the server contains a token - usually something like this:
<ComputerName>%COMPNAME%</ComputerName>
This token/variable will resolve to the unique computer name of each system you are imaging.
Example: if you are imaging Computer1, %COMPNAME% will resolve to Computer1 and that is the name it will have when sysprep runs after imaging. Same goes for Computer2, Computer3, etc...
If for some reason this is not working natively, I can also help you force this to occur with native batch/cmd scripting, but normally this just works out of box.
PS: One prerequisite for this is that the system must be known to the altiris database as the name you wish to keep. If the computer record is brand new to the database it will usually be set to the serialnumber of the system which may be where your hangup is occuring. If the system is known to the database as the serialnumber that is the name it will keep after imaging. To fix this, simply reconfigure the name to "Computer1" so that the database has that value. Once you do this, you can reimage the system and it will preserve the name "Computer1."
If this solves your issue, kindly mark this as a solution. Thanks :)