SysWOW64 is for 32-bit files which are rarely used.
I thought that the name implied that it had the files used for 64 bit processes. However, if it's that way, then the procedure listed by the Spanish guy in that tutorial doesn't work, because I was able to replace the shell32.dll inside System32 with mine from the command prompt and still copying a file brings the default ugly gradient. I specified a totally different one with no light blue at all. Maybe his tutorial was for Vista?