[symphonix]

OK, to summarise what it means, your computer has a certain amount of RAM, which is its "memory". It simulates more RAM by allowing extra data to be saved to the hard disk, which is known as Virtual Memory.
To do this, it breaks your memory space up into "pages". Applications that need access to data that is in memory call the data by page. If an application calls a page and it is in the RAM, then it is a "page in" occurs. If an app calls for a page from memory, and that page is currently stored on the hard disk and has to be read back into the RAM, then a "Page Out" occurs.
A "Page-out" slows the operation of the system down because it has to read the data from a hard disk into RAM first, rather than reading straight from the RAM. Hard disks take about 300 times as long to transfer a page of data, which adds up to slow performance.

If page-outs exceed page-ins, you definitely don't have enough RAM. Ideally, page-outs should be less than 20% of the number of page-ins (the fewer page-outs, the faster your machine is performing) On my machine, I aim for less than 5%.

Adding more RAM, or reducing the number of open applications, are the only ways to reduce page-outs. While freeing up memory by working with fewer and smaller files and apps may help, more RAM is the only reasaonable solution.