Upgrading Memory from 256 to 1GB

can you post the service tag number here so that I can check the full specifications of your Dell.?

Upgrading is pretty easy if you can open your CPU, be careful working inside, if you break or shortcircuit any of the stuff inside, your motherboard might stop working.
here is the video:

Do you have the right memory for your Dell?
Memory Upgrade for Dell Dimension 1100 Computer, the Dell Dimension 1100 Computer takes the PC2700/3200 DDR SDRAM DIMMs. Supports Dual Channel DDR. Memory Type, and comes installed with 128 MB (removable) of Memory. You can upgrade your Dell Dimension 1100 Computer to up to a maximum of 2.0 GB Memory, the system has 2 sockets to install Memory, already with 128 MB (removable) standard Memory installed. For best Computer performance use the maximum amount of allowed Memory per slot for your Computer.
Choose the following Memory Upgrade for Dell Dimension 1100 Computer.

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

yes that memory's specification is compatible. you can use it...

2GB is the maximum amount of ram you can install in your Dimension 2400. Depending on how much ram you have in it now,.. you could get a substantial speed difference by upgrading. You can upgrade the video card if you want. If you want to upgrade to 2 GB and upgrade to a decent vid card,.. you are looking at about $180 for parts. you will need to determine if that is something you want to put into the 2400 or buy a new computer with substantial speed and performance difference for about $500 from Dell. If you have any further questions, please post a comment here and I will answer them for you.

Im sure you mean 1GB of ram.

Upgrading ram is possibly the easiest upgrade to a pc.Firstly shut down the computer and remove the wall plug.

Remove the casing
Make sure you touch something metal away from the case before entering the chassis of the computer... anti static wristbands are good.

As soon as you open the case you will see the dimm slots where the ram goes.

You will find two plastic clips on each ram module, just pull these back to release the ram and insert the new ram.You may need to push firmly down to lock them in.The clips will auto lock.

Just be careful not to push to hard as to damage the mainboard.

You should check with the folks at Dell since whoever wrote their technical manuals for this machine can't do basic math. There are 2 memory slots and each can handle a maximum capacity of 512MB, yet they claim the maximum capacity for the machine is 2GB instead of 1GB. Using 512MB modules would probably work.

You need more memory. If you have windows xp you need at least 512 memory.

there is button at the rear top and rear buttom of the machine. press the button and swing open one side of the machine.
to get to the memories, you have to be very careful about the wiring, it is tight and not much space for you work in. do not lay the machine on its side,

yeah thats a normal issue with the dimension 2400 as the older bios only supports a max of 1gb of memory you will need to go to the dell website which ive linked below and get the bios update which will give you support up to 2gb-pc3200 ddr memory

http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&ServiceTag=&SystemID=DIM_PNT_P4_CEL_2400&os=WW1&osl=en&catid=&impid=