All those people who installed 4GB or whatever amount of RAM and come to see that Vista is only reporting 3300 or some random number can finally relax as SP1 now reports the total installed on the system not just what the OS has available...I guess MS took the "instead of educating just hide it" from the user approach to lessen the complaints from customers about their memory.\n\n\n\nIt is important to understand that not all the physical RAM is available to the operating system. Before SP1, Vista only took into account the system memory that it could use, and ignored the rest, even if it was installed. Because of BIOS and driver reservations of RAM, both 32-bit and 64-bit editions of Vista RTM failed to report the full amount of memory on a system. Vista SP1 comes to resolve this problem, and will provide correct information of the hardware configuration even if the operating system has to share the RAM and can use only a portion of it.\n\n\n\n"On computers that have a 32-bit operating system, more than 3 GB of system memory, and with a version of Windows that is earlier than Windows Vista SP1, users will see a larger difference in how much memory is reported as available to the operating system compared to how much physical memory is installed. This is because some physical address space must be reserved as I/O regions for memory mapped peripherals. These I/O regions are allocated between the 3 GB physical address and the 4 GB upper physical address limit," Microsoft added.