Hi, Strasser.
As John and John said, there should be no problem in using Windows Explorer to make a backup copy of Quicken's data files, so long as you get the complete fileset. This is not the same as Windows' (or Vista's) Backup/Restore, but there should be no problem in using that utility, either.
But I also see little or no need for this. In addition to the 5 most-recent-weekly backups that Quicken makes automatically (in the Quicken\BACKUP folder, by default), I typically have at least 3 other recent backups that I make manually. First, there is the one that I do with Ctrl+B at least once a day, and often several times a day as I complete "batches" of data entry (from checking, from brokers' statements, after bank reconciliations, etc.); this one goes to a separate folder on the same HD as Quicken. At least once a week or so, I'll also redirect the Ctrl+B backup to a folder on a different HD in my computer. Then, about once a month, I'll also send the Ctrl+B backup to a USB thumb drive, which is stored separately from the computer itself. And, sometimes, I DO use Windows Explorer (or Xcopy from a Command Prompt) to copy the whole Quicken folder to still another thumb drive or CD, but I'm not very conscientious about making these copies.
But, no matter how or where I make the backups, I practically never need to Restore one, so I have very little experience with that. I test them now and then, just to be sure that I can restore, but they are for emergencies only, not for daily use.
Once upon a time, when we were using floppies for backup, Quicken had to split the backup files among multiple disks and then do some extra file management to be sure that all the pieces were reassembled properly when restored. And there was a time when the backups were encrypted and the restore program had to decrypt them, too. But those complications are behind most of us. Nowadays, I can't see any difference between files created by Quicken's backup and a straightforward Copy, by either Quicken or Windows.
RC