This BATCH File will take every number sequenced file name and rename it starting with 100001 and increasing by 100 for each file.
This will only work if the file starts with a sequency number followed immediately by an underscore:
EX: 100020_Some name_here.txt 1_Some name_here and stuff.xml
This BATCH File MUST be in the same directory with all of the files that you wish to rename.