OpenEuphoria

No Typo.
A regular 32bit os such as windows 7, vista or xp can only ADDRESS 4GB of memory.
Out of that 4GB you have to have room for video memory and some other devices etc.
So if you have 3GB memory installed its fine, but when you have 4GB installed memory some of the memory addresses are used instead for video memory etc. which is why even with 4gb you can only usually use about 3.15-3.25GB in windows 32bit.

There are good instructions available from Microsoft on how to use memory above 3MB,