Hi,
 
from my knowleadge, spaces characters are illegal in graphics names...  I also found some comments on that at http://groups.google.com/group/comp.text.tex/browse_thread/thread/b210a8adc417be12/71a8fe287441617b?q=graphic+space+%22file+name%22&rnum=1#71a8fe287441617b
 
I would recommand "Total Commander" as a good program to operate a multi-renaming operation...
 
Good luck !
 
Corentin