According to the datasheet 1GB is the maximum. More isn't reasonable for your intended tasks.
I doubt whether it will become faster. This will only be the case if it swaps a lot at the moment. The same goes for the temperature and therefore for the noise. Maybe cleaning the fan and the grill will have a better effect.
i am in the same situation, i really need to upgrade my amilo d 7820 with some more ram. the manual i downloaded doeas say that it takes 2 gb. max, have a look here: http://www.kimgar.com/_files/amiloram.jpg
i've been looking for 1 gb. 144 pin ram without success, is it possible? does it even exist?
or to be more specific, 1 gbyte PC 266 DDR So DIMM 144 pin JEDEC