I've been learning about deploying Server 2008...editions, roles, features, etc.
::> The roles are: AD, DNS, DHCP, File (big upgrade from 2K3), Print, WSS (SharePoint), NAP (Network Access Protection), TS, IIS, and WDS (Deployment).
::> "Server Manager" in 2K8 replaces "Computer Management" in 2K3.
::> Editions: Web, Standard, Enterprise, Datacenter.
:: ::> The Web edition is identical to Standard except it only runs IIS. Standard doesn't offer ADFS (a type of single-sign-on), nor does it have as many features for handling certificates (such as an online responder or network device enrollment (for hardware which (naturally) doesn't have a domain account)). I'm not clear on what the "online responder" is all about. Standard is also "limited" to 32GB of RAM and 4 CPUs in a 64-bit configuration (4GB in 32-bit mode).
:: ::> Enterprise is the sweet-spot with up to 32GB/2TB of RAM (depending on 32/64-bit mode) and up to 8 CPUs. Enterprise also seems to allow you to legally run up to 4 additional installations in a virtual Hyper-V environment!
:: ::> The Datacenter edition can be scaled up to more CPUs - 32/64 for 32/64-bit respectively (you pay per CPU and user) and lets you legally run as many virtual installations of Windows Server as you dare!
:: ::> Pricing at the moment (from CDW.com) is $400 for Web, $740 for Standard (with 5 CALs), $2,900 for Enterprise (with 25 CALs), and $8,200 for Datacenter (4 CPUs). Info on licensing.
Let's say you have a limited-purpose perimeter server with some Internet exposure. You can reduce its attack surface by installing just "Server Core" which is the same as what you'd have normally, except all administration is done via Shell rather than GUI. It also doesn't support managed code in the form of .Net or ASP.net. Core also doesn't support ADFS, failover clustering, WDS, and probably other stuff too. It doesn't have an explorer.exe process. It's especially recommended as a foundation for Hyper-V guests (maximum performance).
About Windows PE and the Windows AIK..."PE" stands for Pre-execution Environment.
For upgrading from Server 2003, you have to boot into Windows and then insert your DVD - booting off the DVD only permits a clean install. AIK answer files for 2K8 are in XML (vs *.inf text files in the past)
Regarding WDS (Windows Deployment Services) and its images (*.wim file - "windows image"). WDS is a role. You can configure it to communicate with all PCs, no PCs, or only PCs in Active Directory. Well, you may ask, what if you want to use it with a brand-new PC? You "pre-stage" that PC by adding its MAC or GUID to a new "managed" computer account in AD.
Quite interestingly, you can use WDS to "capture" an existing server/PC image and save it for future reference. If you plan to roll that image out to additional boxes, be sure to use sysprep first. ImageX can be used to apply updates to an image.