Memory holds the information that you are working on in afast and quickly accessible manner. Building your computer today will require the purchase of memory or RAM(random access memory).  When you look topurchase your memory for your new PC you will work with DDR2 (Dual Data Rate)memory.  This new DDR2 memory has severaladvantages over its predecessor, DDR, lower power consumption, betterpre-fetching and 240 contacts on the chip versus 184 contacts on DDR memory. 

As with DDR memory you might want to look at the fastest chipspeed that your motherboard can handle. For most of us let’s concentrate on the amount of RAM andconfiguration.  By buying memory in pairsyou can take advantage of improved performance offered by DDR2.  Ultimately, this question is best answered bylooking at the recommendations of the motherboard manufacturer you choose.

Another important item is to understand what you are looking to do with your computer and what operating system you will be using.  If you are looking to install Windows XP 32-bit or Vista 32-bit then you will not be able to use more than 4GB of RAM.  Most people looking to surf the internet, type a few letters and play some card games could do OK with 1-2GB and Windows XP.  I recommend that you start with 2GB if you are considering Windows Vista.  Also, don’t forget that there are Open Source alternatives like Ubuntu, a great Linux flavor that is easy to get around for a Windows user.