This is how I collect it, might work for you:

DECLARE

@value VARCHAR(64),

@key VARCHAR(512)

set @key = 'HARDWARE\DESCRIPTION\System\BIOS\';

EXEC master..xp_regread

@rootkey = 'HKEY_LOCAL_MACHINE',

@key = @key,

@value_name = 'SystemProductName',

@value = @value OUTPUT;

SELECT @value as 'SystemProductName'