[unleash]

and by the way,

winXP isn't made to use 4GB, It is programmed up to 3GB and therefore you have 1GB of RAM that's can't be used by any programmes on you system. Vista is programmed to be able to use op to 10GB(but this can be more due to upgrades or such). So if your OS is winXP than you won't be able to use your systems full potential. There are ways around that, but that's to difficult to explain on the web, for me that is.

I think your best option is to go for the 3GB switch, but I guess this will only make photoshop faster and will not enhance the rest of your system...