NvCpll.dll error

I tried installing the latest Nvidia drivers, unfortunately, they do not work.

This is the error I get

“Error loading c:\windows\system32\nvcpl.dll
c:\windows\system32\nvcpl.dll not a valid Win32 application”

I have an AMD 3800 X2
2 GB RAM
320 GB HDD

I run Windows Vista Ultimate.

Please someone help me out.