I know a bit about JBOD, RAID 0, 1 etc... But I'm a bit confused about what kind of Enclosure will give me acces to two distinct hard drive, on wich I'll be able to write stuff as I wish. I found this: http://www.anandtech.com/storage/showdoc.aspx?i=3179
but it's written Linear 1 and 2 ... What are the differences?
I haven't seen the term used before, but from the description in the article it appears that "Linear" is equivalent to "JBOD" - in other words you'd have two independent hard drives that look to the system like two independent hard drives and which do not use RAID in any sense. Assuming you put one partition on each drive then they'd appear to Windows as two separate drive letters.
Of course that's just one of the options, according to the description you could also configure the two drives as RAID-0 or RAID-1. In a RAID configuration, again assuming you use one partition, both disks would be combined into a single RAID volume which would look to Windows like one drive letter.
Wait, the product site says that "Linear" means that NO RAID structure is used, and both drives are treated as individuals. Only the "Big" setting uses JBOD, in which the two drives are joined by the Muse controller board to appear to be one large drive. Discoduck got it right. I'm still trying to figure OP's question, though. OP says "but it's written Linear 1 and 2 ... What are the differences?". Indeed, the product description on the site linked does not use those terms.
OK, now I see what this is. OP, there is a diagram on the front of the unit that tells you how to set two DIP switches to set the mode of operation. The DIP switches are the two in red, labeled 1 and 2. The diagram says if you want Linear Mode (the one with two independent drives), you must set them so that both switches 1 and 2 are Off. If you want RAID0 mode, you set switch 1 Off, and switch 2 On. Etc.