What are the good effects if I replace my 256(mb)RAM to a 1(GB) RAM?

Everything is faster, from loading internet pages, to start up, to opening applications because now that you have more ram, your computer can spend less time reading the hard drive, it can save it into a fast storage area (ram) for quick access. So everything will be much faster, but how fast the ram is also depends on the speed your ram can handle, so does the specs of your computer.