Compatible memory for my PC

A couple of years ago I built a desktop based on a Gigabye GA-X38-DS5 Socket 775 (Rev 1.0) motherboard.  I installed 2 x 1GB Kingston Hyperex DDR2 (KHX9200D2K2/2G):

2GB 1150MHz DDR2 PC2-9200 Non-ECC CL5 (5-5-5-15) DIMM

The full data sheet for this memory can be seen here:

I've just installed Windows 7 64 bit on my PC, so it now dual boots into XP or Windows 7 and I would like to install more memory into the 2 available slots on the motherboard.

I can find one supplier of the same memory I already have, which would give me 4GB in total, but I'm looking to go to 6GB and I can't find my existing memory in 2gb sticks as I would need 2 x 2gb.

As this memory is a couple of years old I thought about getting something newer that would be compatible, but I'm not sure what this would be.  I've found the following on ebuyer:

Kingston 4GB (2x2GB) DDR3 1333MHz HyperX Memory Kit CL7 1.7V

Kingston 4gb (2x2gb) Ddr3 1333mhz Hyperx Xmp I5 Memory Kit Cl7(7-7-7-21) 1.65v

or even this if I decide to stick with 4gb by purchasing 2 x 1gb sticks:

Kingston 1GB DDR3 1333MHz HyperX Memory CL7(7-7-7-20) - This is much cheaper than my original memory, which is available at

I have two questions:

1. Is there an issue installing 6gb of memory on my desktop while still using Windows XP or will XP simply ignore everything over 4gb (or is it everything over 3gb)?  I want to be able to continue to us XP in the short term until all my software is installed and working on Windows 7.

2. Would the above memory be compatible with my existing memory?  It looks to me as though it is faster and one thing I don't want to do is to slow it down as my current memory is very fast.  If it is compatible and faster I'm assuming the speed of my current memory would be the limiting factor.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
1.  XP Will ignore any RAM it cannot access.  The maximum it MAY be able to access is 4 GB.  The amount it can be expected to access is anywhere between 2.75 and 4 GB DEPENDING on the hardware you have in your system  MOST COMMONLY, you'll see about 3.25-3.5 but it could be less... or more.

2.  DDR3 RAM is physically different from DDR2 - you cannot use DDR3 in a DDR2 system.  If you want to buy memory, I suggest you go to one of the common web sites and use their selector tools to identify proper, compatible memory for your system.  For example:
MilleniumaireAuthor Commented:
Thanks for pointing this out.  I decided to purchase another 2gb of the identical memory I already have to ensure it is compatible.  I would have preferred more, but it is 2 years old now!
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