I recently had a stress test bug assigned to me that I couldn’t repro on my machine with 6GB of memory. I could have opened the box and physically pulled out a couple sticks, but what fun is that? You can actually restrict the amount of RAM right from Windows.

start > run > msconfig > boot > advanced options
Check the Maximum Memory box and enter the number of KB you’d like to have in your machine.
Reboot and check the system memory to see if it worked

While this isn’t a common scenario for many users, it can come in very handy when you’re developing a new app.