Funnily enough, I did almost the same thing myself this weekend, only I was migrating Gentoo from my IDE hard drive to a new SATA one.
Both things you want to know are explained in this website
: The copying instructions near the bottom, and some advice on the /boot partition (500MB is huge for /boot, 50 is more like it, btw) nearer the top the middle. . . I wouldn't bother using a /boot partition unless I were booting more than one distro, tho.
You'll need a live CD or other distro to copy the files across: Slackware comes with a rescue CD that's perfectly up to the task, IIRC. . .