Question : Installed vs total physical memory

I have a new Dell Vostro 1720 running Windows 7 (32-bit). It reports that I have 4.00GB of "Installed Physical Memory" and 2.99GB of "Total Physical Memory".
Why the difference?
Thanks.

Answer : Installed vs total physical memory

This is a very popular question.  See the great replies posted by various experts in this Previously Answered Question at Experts Exchange (which is for Windows XP, but applies to Vista and Windows 7 also):

http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Windows/XP/Q_24113152.html
XP Pro computer with 4 GB memory only showing 3.25GB, how can I get it to show 4gb?