Just a quick question - my main PC at the moment is a Fujitsu Siemens Amilo Li 2727 which I've upgraded to have Windows 7 64 bit on it. As far as I'm aware if I hadn't upgraded the OS to 64 bit I would be limited to 3GB ram (it came with 1GB as standard):
This is what I get recommended when using the memory finder here:
Re: Max Memory for an Amilo running Windows 7 64 bit
Unfortunately the 2GB limitation is a feature in your computer's motherboard and BIOS, not in the operating system. So even though your new operating system is capable of reading 4GB or more, the hardware in the laptop is limited to 1GB per slot.