First of all...congratulations on your decision to go from Me to XP...wise decision...
Next...can you tell me how much memory is installed on your computer?
XP actually compensates for programs that use a lot of memory, so there is really no need to adjust your virtual memory settings, however, you may want to read below...
You may want to rethink your decision to use Norton Internet Security. I used to be a firm supporter of Norton products...and although they do the job, they are certainly memory resource hogs. In order to for your computer to function properly, after installing a Norton product, you'll have to purchase more memory in order for your PC's performance to improve. This is especially true after installing any Norton product.
My recommendation would be to find other alternatives to your decision to use Norton. There are free products out there that perform as well, if not better than, Norton products.
For example:
Antivirus:
AVG Free EditionSpyware:
SpyBot Search and DestroyFirewall:
ComodoWith the above in mind and your answer to how much memory you have installed on your computer...we'll be better suited to assist.
I hope you have found this information useful...