I don't have additional information, but can just confirm that you are right that any 32-bit operating system will not see the full 4GB. I have an Intel Atom net-top computer with 4Gb installed, it will only work with Windows 7 32-bit, not 64-bit, as this processor is not 64-bit compatible. Windows sees about three and a bit GB.
In real terms if you buy that fourth gigabyte, you are really getting a lesser amount for your money, as long as you are running 32-bit. Yet, I don't think there are many situations where the PC would perform much better or worse depending on whether it had that last fraction of a gigabyte.
Financially, if you're going to upgrade to a 64-bit OS in the future, and upgrading from 3 to 4 GB, you will be paying now for 1GB and later another 2GB chip to replace it. If by then the cost of a 2GB chip has come down to what a 1Gb chip is now , then you have lost nothing. If the 2GB chip is still expensive, then it would have been better to buy the full amount in the first place. (I hope this logic makes sense)
You may even end up wanting 6 or 8GB in the future, which would mean buying new chips anyway. Personally, I like the argument "I can always get more later".
In real terms if you buy that fourth gigabyte, you are really getting a lesser amount for your money, as long as you are running 32-bit. Yet, I don't think there are many situations where the PC would perform much better or worse depending on whether it had that last fraction of a gigabyte.
Financially, if you're going to upgrade to a 64-bit OS in the future, and upgrading from 3 to 4 GB, you will be paying now for 1GB and later another 2GB chip to replace it. If by then the cost of a 2GB chip has come down to what a 1Gb chip is now , then you have lost nothing. If the 2GB chip is still expensive, then it would have been better to buy the full amount in the first place. (I hope this logic makes sense)
You may even end up wanting 6 or 8GB in the future, which would mean buying new chips anyway. Personally, I like the argument "I can always get more later".
