Windows has a path length limit of 255 chars. If you are going to copy a bunch of files around that are contained within a deep hierarchy, you run the risk of hitting this limit.
To check the length of the longest file name including the entire path length, use this PowerShell script.
cd "C:\MyDir"
$len=0;dir -r|%{if ($_.FullName.Length -gt $len) {$len=$_.FullName.Length}};$len