forsyth

Yep. Using more than 4GB with 32 bit Windows is certainly "guilding the lily". A 32 bit OS can't address more than about 3GB. Which is why all my future PCs, particularly the ones I do serious work on, will run a 64 bit OS. My laptop runs 64 bit Win 7, with 4GB onboard (which I will probably increase).

How Much Memory Do You Really Have?
When you look at the specifications for a computer, it will display the installed memory, and typically the maximum memory that can be installed. However, while these are real values, they represent a potential useable memory depending upon the installed operating system, and other factors. The actual useable memory may be different (lower) from these values. The reason is simply that a computer may have a limitation in the operating system (such as Windows 32 bit versions), or configured to use shared memory, which reduces the amount of RAM that is available to the CPU by using some of it for other purposes, such as for video memory. In some cases, you can control the maximum useable memory through system settings, by upgrading from a 32 bit to a 64 bit version of Windows XP or Vista, or by upgrading to a video card that has internal onboard video memory.