Well, it is true because with the extra memory, data does not need to wait for the temporary data to be flushed out from the 1GB but instead just store data on the extra 1GB of memory. That will speed up the application(s). That is why it is really important for you to install 2GB of memory on your desktops/laptops.
What if you already have 2GB instead in your system? Do you need more than 2GB of physical memory in your system? I have tried 2GB and then 4GB and then 8GB (quad channel) on my system. Guess what? You can't really see significant difference having installed 4GB or 8GB of memory in your systems. I think installing 4GB of memory will be sufficient unless you are a multi-tasking user like me. If you are, paired the 8GB with a quadcore CPU will really speed up your system.
When you have more than 4GB of memory, it is vital to know that you need 64 bit of OS to be able to recognise the additional memory and use them. Otherwise, it will be such a waste for you install the additional memory. At one time, I had 8GB running on Windows Professional XP 64bit with a decent Nvidia Gforce 9800 GTX+. I ran F.E.A.R. 2 on it and boy, it rocks!!! Just to let you know that with 8GB, you will need a better PSU. I think a 700w PSU will be sufficient. Although I know that my GForce 9800 GTX+ is not the fastest graphics card around town, it can still produce decent frame rates. I could run NFS Undercover in the highest settings and I still manage to get around 40fps. It is brilliant!
Well, 2,4 and 8GB of memory configurations are only useful if you are running on non Intel i7 CPUs. If you are running on the i7 CPU, it is wise that you are using 3,6 or 12GB memory configurations because the CPU is designed to run on triple channel. I have not been able to use any Intel i7 CPU until now. I might build myself an i7 system but I am just waiting for the price to come down. At this moment, I don't think it is justifiable for anyone to get the i7 as it is still very expensive. Moreover, better CPUs are releasing very soon. Well, stick with your current Core 2 Duos and it will be just fine, trust me. It will be much wiser for your pockets but...
Yes, with 8GB of memory is much better than 2GB. I am using a Compaq 2800 series laptop and Compaq said that it can only take 1GB of memory. What I did was to replace the 1.4Ghz p4-M to p4-M 2.2Ghz and upgraded the memory from 1GB to 2GB. It really make a vast difference!!!