Vista x64 to Win 7 x64

I am trying to do an upgrade from Vista Home 64 bit to Win7 Ultimate 64 bit, but every time I do, I get an error that says the versions are incompatible. I forget the exact wording, but it literally says cannot upgrade 64 bit version to this 64 bit version, depsite the fact Win7 Ultimate is reported to be compatible with everything. I even tried to do the x86 install after x64 failed out a few times (I know, I didnt actually expect it to work). I honestly think that this version of Vista was so chewed up that it's failing due to corruption in Vista, when I got this machine to work on it was crawling with viruses (Vundo, doesnt open .exe's, all the fun stuff). Usually I just do a clean install, but the lady who gave me this machine begged me to try and save her programs. I can honestly say I've never seen this incompatibility error before though, any ideas?

Have you run a chkdsk on her vista drive? Disk corruption can hamper an install.

Well if it was that screwed up I would load Ubuntu from CD save her documents, photos, music, favorites, and desktop items and do a fresh install. After you install fresh have her load all her Apps then help her make a image for next time.

I don't think I would try to upgrade a pc that has been infected with viruses, or was otherwise unstable.
It looks like that option is closed to you anyway.

You should be able to run windows easy transfer to export all of the user settings and user files to an external device.

Do a clean install of windows 7 64 bit, and import some or all of what you saved.
Apps will have to be reinstalled.

It might be a good time to upgrade, and do the new install on a SSD. The performance gain will be noticeable. Then reformat the old hard drive for overflow and storage.