I tried another way to get the files from my real machine to the virtual machine.  I used the Virtual CD Control Panel to mount the ISO on my real machine, then copied them to a folder on my real machine, then shared that folder over the network.  I then accessed the share from my virtual machine.  Same error.  Here's the actual error:

Error 1335. The cabinet file '_1584_RTL_x86_enu_MSHelp_Data_Services.cab' required for this installation is corrupt and cannot be used.  This could indicate a network error, an error reading from the CD-ROM, or a problem with this package.

I'm going to re-download the iso just to see if it is corrupt somehow.