Running a Desktop and Laptop each with Windows Vista Home Premium32 bit. Plan to upgrade each to Windows 7 64 bit. Have been given two answers as to the maximum memory permitted in each system. One individual advised the max is 4 Gb in each which is determined by the motherboard. Dell Inspiron 1420 and Dell XPS 410. The other answer is Windows 7 64 bit will permit the use of more memory. Who is correct? What determines the max memory in a system? The operating system or the motherboard?