Can swapped space from hard disk be used to increase availability of RAM for playing games etc. on Windows XP?? Can anyone tell me how to do such a swap??
The simple answer is NO. In order for virtual memory to come into play you usually have already run out of RAM. Increasing virtual memory will not increase the amount of physical RAM you have available. In fact it will slightly decrease it since the virtual memory manager uses RAM to keep track of the virtual memory, but in the process it will allow you to run larger programs than you normally could. Those programs will run slower - sometimes MUCH slower - but they will at least avoid a system crash (up to the point where you run out of virtual memory too).
Back to your original problem. There are several threads on SU that discuss how to reduce XP's memory footprint. You might want to continue your search there.
Swap space is used as ram by Windows, It's a LOT slower than RAM, so if you can afford to your computer will take more ram, do that. With that said, here's how you change swap settings:
By default Windows XP will increase the swap space as needed. Under normal circumstances, you should not have to mess with this.
You can change it by right clicking on "My Computer" and selecting Properties. Go to the Advanced tab, Push the Settings button in the Performance section, then go to the Advanced tab then Change in the Virtual Memory section.