Your usage of Skype will probably depend more on the available bandwidth of your internet connection than it will depend on your computer.
You have enough ram.
You might want to look at the size of your page file and set the maximum a little higher - it normally should be about one and a half times the amount of ram you have and if you just installed an additional 512mb you can increase it.
If you still experience a problem you can increase it a little more - maybe twice or even two and a half times the installed ram.
If you have a secondary internal hard drive installed move the largest part of the page file to it, at least one and a half to two times the amount of ram leaving a small page file on your primary drive. Windows will use the file with more capacity automatically but place minidump files on the page file only on the primary drive - so it is necessary to have some capacity left there.
Placing the active page file on a slave drive will actually make it a little faster and create less fragmenting of your primary drive where the op system resides.
Optimize the Page File
"Virtual Memory is the space on the hard disk Windows uses as RAM. The Page File (Pagefile.sys) serves as temporary, virtual memory storage for code and data." - Source
Instructions - Go to "Start", "Settings", "Control Panel", "System", "Advanced" tab, in the "Performance" section select "Settings", "Advanced" tab, in the "Virtual Memory" section select "Change". Change the values to:
- Initial size (MB): 1.5 x the amount of RAM in your system
- Maximum size (MB): 3.0 x the amount of RAM in your system (PF Size Limit = 4095 MB)
Then select "Set" and "OK" and reboot.
Notes - Windows XP by default is set to use only a Dynamic Page File that can resize during normal system operation, consuming resources and causing file fragmentation. A properly configured Page File will not resize (increase) so long as the Initial size is set large enough. Allowing the Page File to resize for rare unforeseen memory intensive situations will prevent "Out of Memory" error messages from occurring. Any resizing will reset to the default Initial size upon reboot and will not cause any permanent fragmentation of the Page File. If you experience frequent resizing of the Page File, a permanent solution is to add more RAM to your system. It is a good idea to have at least 1 GB to 2 GB of RAM in a PC today. A simple test to determine if you need more RAM is to use you PC for a whole day without rebooting, then look at the Task Manager (Ctrl-Alt-Delete), Performance tab. If the "Commit Charge - Peak" is ever higher then the "Physical Memory - Total" your system could benefit from adding more RAM. When you change the amount of RAM in your system, you have to adjust the Page File size.
Advanced - "Moving the Page File to a separate physical Harddrive (not partition) from the boot partition will increase Page File performance. However, if you remove the paging file from the boot partition, Windows cannot create a dump file (Memory.dmp) in which to write debugging information in the event that a kernel mode Stop Error message occurs. The optimal solution is to create one paging file that is stored on the boot partition, and then create a second paging file on a separate physical Harddrive (not partition) Windows will use the pagefile on the less frequently used partition over the pagefile on the heavily used boot partition. Windows uses an internal algorithm to determine which page file to use for virtual memory management." - Sourcehttp://mywebpages.comcast.net/SupportCD/OptimizeXP.html