I am using Windows XP updated to Version 3. Under the SYSTEM information it states that I am running Intel Pentium 4 CPU 2.60 ghz, 480 MB of RAM. I know it is a single strip of RAM. I also know that I can have a larger amount of RAM. So how do I know when I purchase a upgrade chip that I select the best one for my system. Additionally should I buy one new Ram strip at the largest one comparable with my PC or would a second chip the same size as the one currently installed be the way to go. I am open to options so any advice is greatly appreaciated. My Thanks goes out to everyone that takes the time to assist the rest of us.

You can go to the system manufacturer and see what they call out for additional memory chips. It should give you the rating you need before you purchase.

One place is RAM Memory Upgrade: Dell, Mac, Apple, HP, Compaq. USB drives, flash cards, SSD at Crucial.com

You can also download cpuid and it will let you know what type of memory is installed on the board now
CPUID - System & hardware benchmark, monitoring, reporting

As far as what max you can use or max for each RAM slot, that depends on the boards specs, you can go to homepage of the model of the system and find out what max is and how much each slot will work with