You've undoubtedly already encountered it whilst using Explorer to copy files. One error and *bam!* everything stops.
That said, the [link|http://en.wikipedia.org/wiki/Xcopy|Wikipedia page on XCopy] suggests using [link|http://en.wikipedia.org/wiki/Robocopy|Robocopy]. It's in the Windows 2003 Resource Kit, downloadable [link|http://www.microsoft.com/downloads/details.aspx?familyid=9d467a69-57ff-4ae7-96ee-b18c4790cffd&displaylang=en|here].
Wade.