There has been some confusion of late regarding the use of OSD feature pack to deploy Windows Vista through WDS.  Let me take a break in discussing OSD in SCCM 2007 to discuss this topic.

There are a few requirements of OSD, WDS and RIS that don’t seem to add up.
-Vista deployments require WDS
-The OSD feature pack (which fully supports Vista deployments) does not support WDS
-OSD feature pack fully supports Remote Installation Services (RIS), the predecessor to WDS, which cannot be used to deploy Vista.
-RIS does not support Windows Image (WIM) format image files, which are required by OSD feature pack.
-WDS does support the WIM format but does NOT support the WIM images produced by OSD feature pack.

I’ve done a bit of work lately exploring the use of WDS for OSD deployment of Vista.  A brief summary of the technologies might be helpful to start.  Both WDS and RIS are stand-alone deployment mechanisms that can be used to deliver an operating system to PXE booting target machines.  The operating system (XP, Windows 2000, Windows PE) being delivered can be a standard OS load (like installing from CD)  or a fully customized image.  OSD feature pack supports RIS but does not use RIS to deliver OS images.  Instead, OSD feature pack uses RIS to deliver it’s own customized version of Windows PE.  Once loaded, Windows PE will interact with the SMS infrastructure and facilitate image install.  So, the image installation isn’t really driven through RIS, but is being driven by the OSD Windows PE image that was loaded by RIS.  By relying on the OSD feature pack version of Windows PE to handle the interface to SMS, we avoid many of the incompatibilities mentioned above.   

So does OSD actually work with WDS?  Yes, it works just fine.  WDS is an upgrade to RIS and offers three modes of operation, two of which allow RIS compatibility.  Legacy mode describes a scenario where the RIS server has just been upgraded to WDS but no WDS configurations have yet been made.  Here, the WDS server will operate but will only offer RIS functionality.  Mixed mode describes a scenario where the RIS server has been upgraded to WDS and configured to act as  WDS server.  Here, the WDS server will work with WDS images as well as RIS images.  Native mode describes a WDS server installed on the Longhorn OS.  Here, WDS will not offer any RIS compatibility.

OSD feature pack can fully operate on a WDS server, provided that WDS server is running in legacy or mixed mode and is configured in the same way a RIS server would be configured.  Below are the steps I used to configure WDS to deliver the OSD Image Installation software as a boot choice.

-Install RIS and DHCP on separate servers.
-Configure RIS using RISETUP.  Part of this process is providing a location where RIS can access either WIndows XP or Windows 2003 files from the CD.  It ultimately doesn't matter which is chosen as our concern will be configuring RIS to boot a PE image, which is the next step.

-Configure RIS to deliver the OSD feature pack version of Windows PE using KB article 304992.  This KB article describes two methods for deploying Windows PE – I chose the RAM disk method with success but others have reported the overlay methods works the best.
-Test a client to ensure RIS is functional and responsive to PXE boot requests.
-Download the Windows Automated Installation Kit (WAIK) which contains the WDS upgrade.  Upgrade the RIS server to WDS.
-Import a boot image to WDS.  The boot image must be named boot.wim.  Most any WIM image could be used but commonly, the boot.wim from the Windows Vista CD is used.  For OSD, It doesn’t matter iwhich image is chosen here as we will be relying on the RIS functionality of WDS, not the WDS boot image.

When configured in this way, the OSD Image Installation software will show up as a legacy image as shown and will be accessible during PXE boot by choosing the RIS option on the initial boot menu.  The action will hand over control to the RiS OSChooser menu which will be familiar to those users accustomed to RIS.

WDS screenshot