In modern operating systems, including Windows, application programs and many system processes always reference memory using virtual memory addresses which are automatically translated to real (RAM) addresses by the hardware.  Only core parts of the operating system kernel bypass this address translation and use real memory addresses directly. 
Virtual Memory is always in use, even when the memory required by all running processes does not exceed the amount of RAM installed on the system.
An expanded version of this article is available at:
http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm

Brief from the article…

Here's a list of how much RAM the various Windows versions and editions support (as of May 2010):
Windows NT 4.0: 4 GB
Windows 2000 Professional: 4 GB
Windows 2000 Standard Server: 4 GB
Windows 2000 Advanced Server: 8 GB
Windows 2000 Datacenter Server: 32 GB
Windows XP Professional: 4 GB
Windows Server 2003 Web Edition: 2 GB
Windows Server 2003 Standard Edition: 4 GB
Windows Server 2003 Enterprise Edition: 32 GB
Windows Server 2003 Datacenter Edition: 64 GB
Windows Vista: 4 GB
Windows Server 2008 Standard: 4 GB
Windows Server 2008 Enterprise: 64 GB
Windows Server 2008 Datacenter: 64 GB
Windows 7: 4 GB

Taken from Microsoft Support Article http://support.microsoft.com/kb/2267427

Microsoft DPE India – Academia has an annual event spanning across 100 Cities in 100 Days. We call it Microsoft DreamSpark Yatra., targeted towards students.

I am extremely happy to be a part of Microsoft DreamSpark Yatra. An unique opportunity to interact with extremely talented & enthusiast students across the country. I will be presenting for this first event on 28th January 2011 at Atharva College, Navi Mumbai, India. If you are coming, do catch up post session.

Keep visiting Microsoft DreamSpark Site to know more. http://www.dreamsparkyatra.com/default.aspx

Wish you all a very happy new year.

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Announcing Microsoft TechEd India 2011, March 23-25 | Bangalore. Visit http://www.microsoftteched.in/

We are BACK with the largest technology event of India this year – the Microsoft Tech.Ed India 2011. REGISTER NOW to attend the conference for hands-on learning, deep product exploration and opportunities to connect with industry and Microsoft experts one-to-one.

The annual Microsoft Tech•Ed India 2011 is back. Join us for the largest technology event at Bangalore between March 23 - 25, 2011.
Microsoft Tech•Ed-India 2011 is the premier technical education and networking event for tech professionals interested in learning, connecting and exploring a broad set of current and soon-to-be released Microsoft technologies, tools, platforms and services.
This 3-day event will focus on technical education, product evaluation and community. The event will include: Keynotes by Senior Microsoft Executives, Breakout Sessions, Hands-on-Labs, Instructor-led Labs, Product Team Tents, Free Microsoft Certification, Community Programs, Solution Expo, and many more social gatherings and opportunities for networking everywhere you look.
REGISTER NOW to attend the conference for hands-on learning, deep product exploration and opportunities to connect with industry and Microsoft experts one-to-one.