'''RAM and HD are like car Engines and Fuel Tanks'''...'' putting more gas in the take wont change the horsepower, increasing the horsepower doesn't change the size of the gas tank.''
Your machine can run a max of 2GB RAM 2x1GB chips (that's limited by what the CPU can manage).
Your max HD is '''limited by space, heatand backward compatibility issues '''(realistically up to 500 or 750GB should be plenty of space). ''Your 9 yr old machine uses SATA I (1.5Gb/s) transfer speed... many of todays SATA III drives claim to work with SATA I -''' but there have been complaints about those that don't play well, hanging and freezing.''' '' Whatever drive you buy ensure that the vendor guarantees it will work and will swap/replace the drive if it doesn't.''
''If this Answer is helpful''' please remember to return and mark it''' Accepted. ''