Jet missing from Windows registry - need to set TypeGuessRows

I have Windows 7 and Excel 2010.

I cannot find this in my registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\Engines\Excel

I have up to here:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft

but no Jet

I need to set the registry value TypeGuessRows to 0 because I am trying to import from an excel spreadsheet and data is getting cut off at 255 characters (plus a null I assume = 256)