Uploading bulk volumes of documents into WSS or MOSS can be problematic when file names with reserve characters are encountered.  A common offender is “&”.  Eg an excel file named   bid & proposal.xlsx     will fail to be imported into a document library. 

I have found a nifty utility originally for MAC but now has a Windows version, that solves this migration / bulk upload dilemma. 

Name Munger (pronounced "Name Munjer") is a powerful, yet simple-to-use batch file renaming utility. Simply drag one or more files or folders onto the Name Munger icon and you can easily add text before or after the existing name, change one or more occurrences of part of the name or even remove some of the name. In a snap you can rename dozens or even hundreds of files.  Main features include:

• Quickly rename one file or a thousand with a simple drag-n-drop
• Add to the beginning of file and folder names
• Add to the end of file and folder names
• Replace text anywhere in a file or folder name
• Remove text from anywhere in a file or folder name
• Strip any character or set of characters from file or folder names.
• Strip leading and/or trailing spaces from a file or folder name
• Change file names to ALL UPPER CASE, all lower case, or Title Caps
• Add customizable numbers before or after the file names
• Renames items in nested folders or just those you select
• Preview your changes before applying them.

Download is available here:   http://sonoragraphics.com/namemunger.html