current client environment: 95% -xp, 5%- linux; we use disk image deployment software for client OS and standard software (like Office, arch, etc). can we find alternatives to Microsoft SMS for automation that tasks? Thanks.
If you've got an Active Directory domain, Group Policy software installation policy can handle a goodly part of your software installation needs. Startup scripts can be written to handle software that is not amenable to installation from MSI files (typically because the manufacturer is too lazy to package them that way-- or in the case of Microsoft Office 2007, because the manufacturer hates itself).
If you don't have an Active Directory domain you could still use startup scripts, configured in the local group policy and referring to a script on a server computer, to do "automagic" deployments to client computers.
The Windows Automated Installation Kit (http://technet.microsoft.com/en-us/library/cc748933.aspx) is the future of the Microsoft "Remote Installation Services" platform used for client OS deployment. I prefer deployment from factory disk images (which then get "worked over" by startup scripts upon joining the domain), rather than automated installation, but either strategy is a valid choice.
(The "Microsoft Deployment Toolkit" is the follow-on to the WAIK described above, but it's still in beta right now... Beta 2, just came out a few days ago.)
If you go the route of using software installation policy to deploy MSI packages, you'll quickly want to learn how to customize existing MSIs and build your own. There's good information at AppDeploy.com about many different software packages. The Windows Installer XML Toolset is one package that can build custom MSI files, though there are also many graphical MSI builders out there. The Microsoft ORCA tool (see http://support.microsoft.com/kb/255905), available as part of the Windows SDK Components for Windows Installer (or other places-- just search for ORCA.MSI on Goooogle), is a great tool for creating transforms (modifications) for existing MSI pacakges.
Edit: Patching -- for the nitpicky... >smile<
For Microsoft applications, WSUS is the way to go for sure. If you have to deploy hotfixes, though, you may get stuck using startup scripts (since Microsoft never provided the ability to deploy custom updates via WSUS free to the public, as I recall being promised, and eventually put that functionality into the System Center Configuration Manager product).
See my answer on the maintenance of Adobe Reader for a general patching strategy for 3rd-party appliations (non-Microsoft): http://serverfault.com/questions/20390/update-management-for-adobe-acrobat-reader/23483#23483