Still quite not able to understand which RAM to get. I (or rather a family member) has a fairly old Dell T3400, which I assume has two 1Gb sticks (out of I assume a possible 4) and so I was going to get another 2gb (which is over the limit of what the OS can use). Is anyone able to give me the timings of what I should get?
This is the CPUZ output: http://dl.dropbox.com/u/26677509/dad_cpuz.jpg
That memory is DDR2-5300 or DDR2-667(MHz)
http://www.crucial.com/store/listparts.aspx?model=Precision%20Workstation%20T3400&Cat=RAM
Looks like the computer can use DDR2-667, DDR2-800, or DDR2-1066, and either NON-ECC or ECC.
Most likely your computer has NON-ECC RAM installed so you need to match that specification. Also look for CAS Latency (CL) of 5, although timing doesn't really matter that much. All modules should set to the slowest module present.
According to cruical the computer can support up to 16GB of RAM (up to 4GB per DIMM; 4 slots available).
Dell manual states up to 8GB (up to 2GB per DIMM).
I suggest that you get two 1GB sticks of DDR-667 NON-ECC CL 5 (http://www.crucial.com/store/mpartspecs.aspx?mtbpoid=BCF67134A5CA7304), however Dual Channel Symmetric mode only means that each channel has the same amount of RAM installed. Each channel consists of up to 2 DIMMs.
For example:1GB + 512MB + 512MB + {Free} could still be symmetric dual channel.
The SPD tab in CPU-z should tell you how much memory is it each DIMM slot.
The other thing that was needed was a internal hard drive for storage (basically huge amounts of image files). Is WD Caviar Green still a good option?
Caviar Green are Western Digital's low power hard drive. I would recommend Caviar Blue drive, as they are for standard uses. However, Caviar Green hard drives are fine.