Hi denboe. As you admit to being "not technically minded", I recommend that you don't actually replace your old hard drive as this would involve reinstalling all your software. It's better to fit a new hard drive as slave to your existing one. You can then move all your saved data to the new drive, and also store any new documents, photos etc there. You can also set you email program to save your emails to the new drive. I have found Seagate drives very reliable. As your old drive is only 30G I assume that it isn't a SATA drive so this 160G IDE drive would probably be ideal click here.