I have a Dell Dimension 4600 with 256mb of RAM and I am looking to upgrade, only thing is I don’t really know where to look or what to look for. 
What I’m hoping the Dopers can do is help me find a nice cheap upgrade that will work with my system, preferably UK based so the shipping doesn’t cripple me.
Thanks guys. 
from: http://support.dell.com/support/edocs/systems/dim4600/en/4600i/sm/specs.htm#1119251
Memory Architecture
Dual Channel DDR SDRAM
Memory type
PC2700 (333-MHz) or PC3200 (400-MHz) DDR SDRAM
(non-ECC)
Should be very straightforward. This is fairly common stuff.
Microprocessor type
Intel® Pentium® 4 that runs at 2.26, 2.4, 2.533, 2.66, 2.8, or 3.06 GHz internally and 533 MHz externally, or 2.4, 2.6, 2.8, 3.0, 3.2, or 3.4 GHz internally and 800 MHz externally
So the question is what’s in there now?
TuneUp system info says Intel Pentium 4 CPU 3.00GHz 3000MHz.
Does that help?
Do you have a video card, or is it on board video?
How far are you willing to go? Do you want to keep the mo bo?
Well, as the only thing I’ve noticed so far is that sometimes it takes a while to switch between apps and for some programs to initialize I was under the impression that some extra RAM should do it really. I have an NVidia GeForce video card but as I said , the only thing I’ve noticed is what I thought was a RAM issue, my video card has been fine up until now.
Go to www.crucial.com and use their memory configuator. Just enter the manufacturer and model number, and they give you the correct memory. Crucial has high quality, fair prices and it is guaranteed to work in the computer you specify. Can’t go wrong.
I’ve done all the steps and found out that I must buy the memory in pairs, does this mean that if I buy a 256mb (which I’ll have to buy 2 of) that I’ll get 256mb of RAM or 512??
Here is a link.
If you add a pair of 256MB DIMMs, you will have 512MB. If you only want 256MB, add 2 128MB DIMMs.
Thank you everybody, all thats left now is to decide whow much I want. 