Are Laptops with 2 drive bays limited to 17 inch models?

[m654321]

Thanks guys for your feedback. I wasn't so much thinking of optical drive to hard drive conversion, or the external drive possibility, but simply what the laptops come with. I like to know what I'm buying. I wanted to purchase a second hand laptop with two drive bays that I could use as my "experimental PC" so if it crashes it won't affect anything important.  Why do I like two drives? A couple of reasons. On the two Asus PCs in our house (see footnote signature), I like to have two separate physical drives because (1) one drive can be used to keep data files separate from the OS drive in a single data partition that spans the entire disk, and the other reason (2) if some of the OS files are distributed between two drives, the OS runs quicker as you have two drive readers working at the same time.

Mike