s71ck

I ran into this same problem but with XP x64. With a 32bit iTunes install to fix it I put sccbase.dll, sccsccp.dll, slbcsp.dll, slbiop.dll and slbrccsp.dll from the above zip file in WINDOWS\SysWOW64\ and it fixed the problem. My guess is when doing the hack to get the Vista x64 iTunes to install on XP x64 that you'll need to do this same thing, possibly using the x64 dlls available on the XP x64 CD in the AMD64\ directory.