I did not fully understand your question, I thought you meant would it work to use that drive, not would your data be safe while installing Windows to it. Personally I would want to format the drive before installing Windows so things are nice an clean after the install, and then move the data back to the drive. Which would obviously erase all of the data on the drive, so you would need to temp store it elsewhere. Even if you don't go that route, I would highly recommend backing up all the data on the drive before installing Windows to it just in case something goes wrong. Borrow a drive from a friend or something like that for a few days to keep the data relatively safe until you've got everything sorted.
Having data that you care about just sitting on one drive with no backups anywhere is never safe, even if its a brand new drive you are taking a fairly large risk in having it setup that way. I would suggest keeping the most important stuff backed up to one of the free online systems like dropbox or skydrive. If you backup only things you can't replace hopefully the online storage would be large enough to help. If you've got piles of movies or mp3's you may not be able to have a backup of these, but at least things like pictures, tax work, addresses, etc would have a safe place.