You can use the migration and deployment wizard by following this artical

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007111409432848

Or elase you can follow this document for Pusing through active directory.

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2008121011454148

Hope this helps:)

Brent, we've found GPO SEP installs to be very efficient and reliable. This series of Articles supplements Symantec's documentation of GPO installs--

https://www-secure.symantec.com/connect/articles/creating-transform-mst-file-control-installation-symantec-endpoint-protection

https://www-secure.symantec.com/connect/articles/startup-scripts-and-sylinkdrop-better-together

https://www-secure.symantec.com/connect/articles/mp-upgrade-path-compliance-using-group-policy

HTH
 

The diffrent ways in Which you can Install SEP  on Multiple computers without uisng the Unmanged option are as follows:

1. You can use altris
2. Microsoft SMS
3 . AD GPO
4. GPO software distrbution
5. Login Script
6. SEPM Migration and Deployment wiazrd

You can find more information about these In the Installtion Guide in CD1/ Doumentation folder. page 87 onwards

You could use the migration and deployment wizard, for sure you have an inventory of your workstation in your office then if you have this write down all the hostname of your pcs to notepad, it should be one hostname or ip per line then you can push install from the server at the same time

You need to decide what options to use while deploying the clients. 
Like If you try to install SEP using Altiris, then you need to first deploy Altiris agent and then SEP.