INDEX
DETERMINING THE AMOUNT OF RAM ACCESSIBLE BY GRUB4DOS
When your computer boots select Grub4Dos boot entry.
You should see something similar to this (the picture is from the net)

What we need here is the numbers highlighted in the picture. These are the amounts of RAM ACCESSIBLE BY GRUB4DOS.
The biggest number there is the maximum size of your RAMDisk.
Now, these numbers reflect the current hardware configuration. You may wanna change that.
Some of you will have an option in bios called something like "Memory Remap Feature". Google it.
You can change your accessible RAM amounts by turning that on/off.
At this point you should decide what version of Windows you will use based on how much RAM you can use.