How to boot 64-bit Boot Image from WDS PXE when only 32-bit will show
This is something that has beeen bugging me ever since I set up our BDD 2007 + WDS setup almost a year ago. Even though I was able to create a 64-bit WIM boot image via MDT and load it onto the WDS server, the 64-bit Boot Image was never shown to me when PXE booting from a 64-bit capable PC. All I could see and boot, was the 32-bit boot images. Argh!
After fruitless searching I resigned myself to the fact that if I wanted to deploy Vista 64 I’d just burn an ISO of the 64-bit WinPE Boot Image and install from there. Fortunately, we rarely need to deploy 64-bit Vista, but this may change soon.
However, just now, I found the solution…
To enable 64-bit Boot Images via PXE with WDS, you need to run this command on the WDS Server:
wdsutil /set-server /architecturediscovery:yes
Why this was never mentioned in the Documentation that I read for MDT/BDD I’ll never know (maybe I just missed it), but finally I can boot to 64-bit WinPE and deploy 64-bit Vista from the network, hooray! 
I found the answer on EggHeadCafe by searching for: “mdt 2008 deploy 64-bit vista pxe”. Roughly half way down the hard-to-read page was the nugget I needed.
For reference, there’s a proper Microsoft KB article explaining the solution.
Really hopes this helps someone out!
Andy said,
24 November, 2009 at 11:45 am
Many thanks, that saved many an hour of head scratching and searching.
Jimmy said,
4 February, 2010 at 9:42 pm
wow, I am so glad i found this.
I was really not looking forward to taking out my frustration physically on this server.
Jerther said,
12 July, 2010 at 8:28 pm
“Why this was never mentioned in the Documentation that I read for MDT/BDD I’ll never know (maybe I just missed it)”
Oh my god you are so right… And no you didn’t miss anything. I went through everything by the [MS] book and this was never mentioned.
From the MS Article you posted:
“By default, architecture detection is turned off.”
What a decision. This is ridiculous…