After making sure that the new drive that you select is compatible with your laptop, get a cable like
this one (Should be available for much cheaper), and use that to transfer your data to your new drive.
I replaced the 30gb Toshiba in my dell with an 80gb Hitachi (7200 rpm). It suffered a strange failure that I was barely able to recover my data from, and I replaced it with the same Hitachi model, but 5400rpm instead of 7200. I have had no problems with that drive, and it actually runs much quieter than the old unit.