Upgrading Vista to 7: Error Code 0x80070005. Mac Induced?

Question

I got my copy of W7 in the mail earlier today, and finally got around to installing. Well, things went pretty much south as soon as I hit "Install." I get a pop-up during the "Setup is copying temporary files" giving me the error code "0x80070005," which, from what I can gather, is a permissions issue.
I've done as much Googling as I possibly can, and no answer has helped. However, each thread I've stumbled across has people asking the creator "Do you have a Mac?," which leads me to the assumption that it's a Mac related issue, moreover, Boot Camp itself.
I know Apple doesn't officially support W7 as of yet - but support is due by the end of the year - but I hear the majority of people don't have an issue.
I don't know what info to list to get the job done, so ask, and you shall receive. I don't want this $50 purchase to go to waste (Amazon pre-order FTW).

Answer 1

Believe it or not, the idea to roll back to Boot Camp 2 came from the following KnowledgeBase article about Boot Camp 3 and XP:
Boot Camp 3.0: Cannot Install Windows XP Service Pack 3
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This was the paragraph that jumped out at me:
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This dialog box appears because Windows is attempting to write to the first partition it sees to install the update. Using Boot Camp 3.0, the first partition it sees is the Mac OS X partition, which is mounted as read-only. This is why the copy cannot complete. In order to avoid the dialog box, complete the steps below to disable the OS X file system read feature so that the Windows partition is the first one that the update sees, then reinstall the update, then re-enable the OS X file system read feature.
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This led me to believe that it had something to do with Boot Camp 3's ability to read HFS drives (i.e. the OS X partition) within Windows. In my case, the AppleHFS.sys file was probably resident within XP at the time I started the upgrade to Windows 7.
For me, I'm fairly certain that it was a clean install - from what I remember, it is not a direct upgrade to Win7 from XP. (hence the emphasis on backing up files)
No need to completely restore and recreate the partition. However, I wanted a simple way to restore my Boot Camp 2 drivers, hence the simple Winclone restore.
(Considering I only upgraded to Boot Camp 3 about an hour before the Win7 installation, I really didn't lose much in the grand scheme of things - except maybe antivirus definitions)
Yet another reason why I am a fan of cloning the OS.