Do you want to make a disk image onto the new drive? Or do you only want to transfer certain data files, like documents, mp3s, videos etc?
If you want to make a disk image, I've always used the Maxtor MaxBlast utility, available at their site. Works with other drives. Your harddrive company should have a similar utility. Anyway, I don't really recommend them much anymore because of the stupid EZBios they install. By the way, you'll need to connect one drive as slave and one drive as master...
To transfer information only, not a disk image, I've always connected one drive as master and one drive as slave, and grab the information off that way. But that involves taking apart your computer, messing with jumpers and cables... might be an easier way, but for transferring large amounts of data... this is the way to do it I think...