This GUI app will do a sequential file re-naming 01,02,03 or 0102,0103,0104. It is very old, I could not find the authors site anymore.
(156k zip 300k single executable portable app called renmfl.exe)
I use it to rename many files for stringing in order. It will load sorted As selected, then put simple sequential numbering on the files loaded in (use CTRL A when selecting whole folder so all files to be in order) . It will also start at a specific number.
It is limited in length of all the file names (quantity of files at a time), due to the file loading method. It will not allow manuel resort of the files prior to numbering (just alphabetical). you can also put a tag on but I never used that feature. YoSemiPic401 , YoSemiPic402, YoSemiPic403 . etc
It only does one type of renaming, but for that type it does it well, it leaves extentions as is, I use a different program for that.
"superb batch renamer" which is about 10 times more complex, will do sequential numbering additions in the Append section, or random, or about anything else you can think of.
(350k Zip 666k portable executable , E-mail ware)
To set a sequentials in it, hit F2 to get into advanced mode, select [x] Append to turn it on, IN the append text entry box Right click, in there is an array of things you can append. One of them being Sorted number.