As you said, with the RAM speed, it will only go as high as the motherboard ill support.
With the HDD RPM, this is just how fast the disk spins around, so there is no limting (except how fast the HDD is deigned to spin obviously)
By all means upgrade, just make sure you
a, get the same type of RAM
b, get hard drive whih uses the same interface
My laptops current HDD and mem is
mem: 200 pin DDR 266 (PC 2100)
hdd: ATA-6 40gb 4200 rpm
would me upgrading to high RPM for hdd and higher speed memory pose a compatability problium?
i know for Desktops that if you get higher memory speed it just goes down to your Mobs max, as for my max RPM for the hard drive i dont know the mx rpm