is there any way that i can make memory free that vistas gets occupied even after i closed the application

Free RAM is ista is using it to cache system and frequently used files. It is normal. IF you search this newsgroup there is a lengthy and ongoing discussion on this matter.
"Gurpreet"

Hi,
It's normal for a program to remain cached in memory for a time after closure, this is part of the memory management model. If it never gets released, that is a different problem. If the demands for memory are high, Vista should release cached code in favor of the immediate demand. As a general rule, Vista tries to use whatever memory is available to it, even if it's just for caching frequently used files. Forcing it free is contrary to design and is likely to slow the system as what is normally cached has to be reloaded every time it is requested.
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP mvp.support.microsoft.com/ Windows help - rickrogers.org My thoughts rick-mvp.blogspot.com
"Gurpreet"

hi i understand that but i have read queries in this newsgroup, people are still not satisfied with vistas performance with even large chunks of RAM, top notch system configs and are switching back to Xp. Why so?
"Rick Rogers"

Some systems are having troubles due to hardware driver problems and is not the fault of vVista. As manufacturers start releasing better drivers vista will start becoming even more stable and much faster than XP. There are many users who are very happy with Vista(Myself included).
"Gurpreet"

Hi Gurpreet,
What you read here are the occasional issues some hardware and software configurations have with Vista. Keep in mind that the purpose of this group is to identify these causes and try to find a solution. So, all that you will read about for the most part are those that are having an issue. The millions that are not aren't posting to tell anyone that, they just go about their normal day. For instance, I am having no performance issues and have done nothing particularly special on the box being used to post this (4GB of ram, Ultimate 64-bit, AMD 3400), nor am I having any trouble on the laptop being used remotely to work from this box (2GB of ram, Home Premium 32-bit, Turion x64).
One of the chief problems seen here aren't performance issues caused by Windows, but rather those caused by users. The root problems are often:
- Misconfigured hardware, whether timing (overclocking) or other BIOS settings - Use of older, non-capable hardware - Faulty/flakey ram - Modifications to the memory manager based on misinformation (like manually capping the paging file or installing third party memory managers) - Installation of non-compliant software, including device drivers - Installation of malware (encompassing viruses, spyware, etc.)
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP mvp.support.microsoft.com/ Windows help - rickrogers.org My thoughts rick-mvp.blogspot.com
"Gurpreet"

thanks.
"Rick Rogers"