Regarding your RAM
Keep the 4GB.
I have 4GB in my 32Bit laptop.
RAM requirements is confusing - but if the system supports 4GB and "sees" only 3GB it does not mean that it ignores 1GB
Your second link explains it better. If you have 3GB RAM your system still needs to allocate memory to the likes of
System ROM
APIC(s)
Integrated PCI devices, such as network connectors and SCSI controllers
PCI cards
Graphics card
Some PCI Express cards (from your link)
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Back to your BIOS update:
I am assuming your system is a Gateway ??
This being the case take a look here
http://support.gateway.com/us/en/product/default.aspx?tab=1
You may need to click on "Change Selected Product" top left
[url=http://support.gateway.com/us/en/product/default.aspx?tab=1][/url]You will need to know Series ( 400 for instance ) and the Model Number.
You will then be able to look at the BIOS
This will be linked to the Motherboard that you have.
If you can get some details of this too it will help.