(1) I dought it
(2) You will not increase your memory, which is ram not HDD size.
(3) If you did, it would run about as fast as pancake syrup left in the fridge over nite. Throughput would be limited to the speed of your USB port - sloooooow. You would NOT be a happy camper
If you want to improve performance,
(1) increase your Ram, Beleive it can go upto 1 Gig (2 x 512M sticks).
(2) You said the HDD was a 74.5 Gig HDD - is it a 5400 RPM, you could probably get a much faster 320 Gig 7200 RPM drive, just verify if it is SATA or a PATA drive.