Increasing memory on K8N-Neo2F

Question

I would like to increase the memory in a home built PC I inherited from a friend who emigrated – but as I am not that knowledgeable I would be very grateful for any advice on the following -
The PC runs Windows XP & is fine but slow, it has 512 MB of memory (2 x 256MB). From the MSI site I can see I could use upto 4  x 1GB and wanted to start by adding 2 x 1GB whilst keeping the eisting 512MB to speed things up a bit.
Problem is there is some much info I can’t sort the wheat from the chaff.
When I ran an SiS scan the existing memory came up as :-
Model : CL2-3-3 Ultra-433
Extended Information : GeiL Dual Channel
Serial Number : 20020725
Type : 256MB DDR-SDRAM
Technology : 8x(32Mx8)
Speed : PC3500U 2.0-3-3-7
Date of Manufacture : 05 February 2002
Set Timing @ 217MHz : 2.0-3-3-7
Am I correct in assuming the “Dual Channel” referred in the SiS scan to is the same as “Double Sided” in the MSI site for this board – and is this also the same as “High Density” which I found on an E-bay site which had warnings about buying high density memory for older boards as it wouldn’t work or would only see half the memory. Also confusing for novices like me is that is that from what I’ve read “Double Sided” doesn’t necessarily mean that the module physically has chips on both sides – it’s merely an expression - yes ?
The MSI site info for my motherboard is below
Supports dual channel DDR 266/333/400, using four 184-pin DDR DIMMs .
• Supports a maximum memory size up to 4GB without ECC.
• Supports 2.5v DDR SDRAM DIMM.
DIMM Module Combination
Install at least one DIMM module on the slots. Each DIMM slot supports up to a maximum size of 1GB. Users can install either single- or double-sided modules to meet their own needs. Please note that each DIMM can work respectively for singlechannel DDR, but there are some rules while using dual-channel DDR (Please refer to the suggested DDR population table below). Users may install memory modules of different type and density on different-channel DDR DIMMs. However, the same type and density memory modules are necessary while using dual-channel DDR, or instability may happen. Please refer to the following table for detailed dual-channel DDR. Other combination not listed below will function as single-channel DDR.
Green
DIMM1 (Ch A)    Purple
DIMM2 (Ch B)    Green
DIMM3 (Ch A)    Purple
DIMM4 (Ch B)    System Density
128MB~1GB   128MB~1GB   -   -   256MB~2GB
-   -   128MB~1GB   128MB~1GB   256MB~2GB
128MB~1GB   128MB~1GB   128MB~1GB   128MB~1GB   512MB~4GB
MSI Reminds You...
• Dual-channel DDR works ONLY in the 3 combinations listed in the table shown in the previous page.
• Please select the identical memory modules to install on the dual channel, and DO NOT install three memory modules on three DIMMs, or it may cause some failure.
• Always insert the memory modules into the GREEN slots first, and it is strongly recommended not to insert the memory modules into the PURPLE slots while the GREEN slots are left empty.
• This mainboard DO NOT support the memory module installed with more than 18 pieces of IC (integrated circuit).
Recommended Memory Combination List
DIMM Slots    Max Speed
Green   Purple   Green   Purple   
DIMM1   DIMM2   DIMM3   DIMM4   
S   -   -   -   DDR 400
-   -   S   -   DDR 400
D   -   -   -   DDR 400
-   -   D   -   DDR 400
S   -   S   -   DDR 400
D   -   D   -   DDR 333
S   S   -   -   DDR 400
-   -   S   S   DDR 400
D   D   -   -   DDR 400
-   -   D   D   DDR 400
S   S   S   S   DDR 400
D   D   D   D   DDR 333
S: Single Side                  D: Double Side
If dual channel = double sided = high density then looking at MSI table the two 1GB modules I want to purchase need to be double sided also (per the last line) to ensure compatibility with the existing 256 (dual channel – per the SiS scan) modules as I would like to leave them in.
When I look at the Crucial and other sites for compatible memory it doesn’t confirm if the memory recommended is “double sided” or not - so do the spec or the numbers of the memory tell me this & I just don’t understand ?
Two examples from the Crucial site are below and I don’t know if one or both would be ok ?
Crucial   CT12864Z335 128Meg x 64   1gb DDR333  PC2700  CL=2.5  Unbuffered Non ECC
Crucial   CT12864Z40B  128Meg x 64 1gb DDR400  PC3200  CL=3   Unbuffered    Non ECC
I note that people on the site talk about changing BIOS timing settings for stability etc – I would really like to avoid having to delve to that level as I don’t feel confident so would really appreciate some (hopefully simple) advice on what would be a straightforward and failsafe way to upgrade my memory.
Like so many things you scratch the surface and find out there’s whole lot more to understand…….!
Many thanks
Julian

Answer 1

Thanks very much to everyone for your kind advice – if I understand correctly I should upgrade to 2 x 1GB and forget trying to use the existing 512MB  as well.
Unfortunately my lack of knowledge means I'm still a bit in the dark.
When I first wanted to upgrade I went on various sites such as Crucial & Corsair and got their recommendations for compatible memory - problem is they don’t specify if their recommendation is high or low density – unless I don’t understand the numbers & letters properly – see examples below:-
Crucial   CT12864Z335 128Meg x 64   1gb DDR333  PC2700  CL=2.5  Unbuffered Non ECC
Crucial   CT12864Z40B  128Meg x 64 1gb DDR400  PC3200  CL=3   Unbuffered    Non ECC
Corsair  VS1GB400C3    DDR-400 (PC3200C3)    2.6v       3-3-3-8-2T
Crucial describe theirs as 128Meg x 64 but Henry says to avoid this  – I assume because 128Meg x 64 means it's high density – does this mean that I can’t even trust a site like Crucial to select compatible memory ?!
The e-bay article linked to in Henry’s reply is also a bit confusing because at the very top it refers to 128M x 64  but then a few lines later refers to 128M x 4 as being high density  and 64 x 8 as being low density yet Henry refers to 128M x 64 as being high density and the Crucial spec above describes it as 128M x 64.
Hopefully you can see why I find it confusing & might be able to enlighten me and/or say what numbers/ letters etc will identify if  the memory is low or high density ?