The honest answer is that you MAY be able to recover the files, and it is mostly a matter of how much is it worth to you to try to get the files recovered.
Depending on how Windows was reinstalled (Clean install, Repair install, Parallel install) and were the files were located in the file structure will determine most of how hard it would be to recover the files.
For example, if the files were in your MY DOCUMENTS folder, and you reinstalled using the same computer and user names, then that file is over written. If you had installed Windows in a different folder on the hard drive and used a different user name, then those files would be in a different folder and you'd just have to search the hard drive to find them. From what you described, your files will not be accessible without the specialized tools of a data recovery expert.
Data recovery is generally and expensive proposition that requires extensive skill and some pretty
software to recover the files. Most people, once they are given an estimate of the cost, decide that the data wasn't all that important.
Some companies you can contact:
http://www.drivesavers.com http://www.ontrackdatarecovery.com/
http://www.salvagedata.com/
http://www.iomegadatarecovery.com/
http://www.actionfront.com/