Changing internal HD to external

[pro240]

I have a second hard drive in my computer set up as a slave. I have recently purchased a macbook and am wondering, if i were to buy an external enclosure for the drive, would i need to format it would would i be able to keep the data on the drive?

Any info would be nice.

 

[prismtx]

I did the same with a new hard drive. I could not get it to format as an external, so I attached it internally, formatted and wrote a couple of test files to it. Then I put it back into the external enclosure and connected it via usb. My test files were there and readable.

 

[pro240]

so it shouldn't be a problem, and the files that are there should be readable once i attatch it externally?