There is definitely something wrong with Windows 7 64-bit and its use of physical RAM. I have an Alienware M17x 4-core with 4 GB RAM. Amongst the reported problems here on this forum with Windows 7's use of RAM I experiened a certain behavior that to me is just plainly unexceptable.
I booted the laptop and then let it settle down out of its boot. At this point it was using just 1.37 GB of RAM. The 4-cores were each equally settled in at idle. I came back 4 hours later after doing absolutely nothing and found that the RAM usage was at 100% with 0% unused RAM.
The computer was at a complete crawl taking over 5 minutes to go from one window to another. It took over 20 minutes to shutdown and turn the computer off.
I have read all the conversations here surrounding this topic and most of them seem to let Windows 7 off the hook. But this is something that Microsoft cannot be left off the hook for. There is definitely a memory leak occurring for some reason or as a result of some feature that Windows is trying to provide to the user.
I think this behavior is totally unacceptable, unwarranted and not correct and needs to be investigated thoroughly to identify the root cause of this huge problem. I cannot buy anyone's excuse posted anywhere in this forum that dismisses this problem. This just isn't correct nor efficient or proficient operating system behavior.