The rules engine in MDT is one of the most powerful ways of applying settings during OS Deployment. It uses INI files that it parses and converts to task sequence variables. For example, this morning I was tagged in a Tweet where a fellow deployment geek was asking about how to name computers based on year, laptop/desktop, and then the last six digits of the Mac Address. Now, for complex computer naming in MDT you typically use a bit of PowerShell, or VBScript, but you can actually use VBScript syntax directly in the CustomSettings.ini file.
Computer Naming Sample
[Settings] Priority=ByLaptopType,ByDesktopType, Default [ByLaptopType] Subsection=Laptop-%IsLaptop% [ByDesktopType] Subsection=Desktop-%IsDesktop% [Laptop-True] OSDComputerName=#year(date)#LAD#Right(Replace("%MACADDRESS001%",":",""),6)# [Desktop-True] OSDComputerName=#year(date)#DAD#Right(Replace("%MACADDRESS001%",":",""),6)# [Default] OSInstall=Y