Error code 0xC00D2B00 when trying to update Zune software

Hello all,
I am attempting to update my Zune software to 2.5 and every time I try to do this through Microsoft Update I get Error Code 0xC00D2B00. It appears as though the update downloads, but when it runs, the update fails.
I have also manually downloaded the update from the Zune website. When I try to install that, I get an error message that says that my current version of Windows Media Center Edition isn't supported and that I need to update to 2005 with Update 2. The link ID in the URL to the update is 101231.
When I first got the Zune, the software worked fine. Now that there's an update, however, I can't even install the software.
I am running XP Media Center Edition v. 5.1 build 2600 service pack 3. I'm not sure how to proceed and would love some help!
Thanks!

User permissions could also be an issue. Log in as administrator.

It sounds like something is preventing the complete file downloading to you PC which is maybe the same reason that Windows Update can't install it either. If you have any download managers on your machine I suggest you disable them and try downloading again.

I only have one Windows "account" and it's the administrator. I double-checked permissions to be sure.
I don't have any download managers. I've tried downloading through both IE and Firefox and I get the same result.
Also, I found the cd-rom with the install software on it and tried using that. That won't work, either.
I appreciate the suggestions. I'm at a loss.