Elegant Solution for Media Library and Backup

Hey guys,

Need some ideas on external storage and backup.

I'm planning to buy a Macbook Air to replace my aging Macbook but the tiny SSD drive will be too small to store my lossless music collection and HD movies (currently around 500GB but will certainly grow over the 4-5 years I intend to use the machine; in this time, 1-2 TB would be a reasonable guess) so I'll need an External HD to store my files.

I also need to backup: I'd like frequent backups to be made of the internal SSD drive but the media library only needs to be protected from accidental deletion/drive failure: there's no need for incremental backups.

The natural solution is to get two disks: one backup disk (media and internal SSD so bigger than media alone) and one for my media library but I want to preserve desk space as much as possible. With two external HD's, I'm going to have a lot of cables, power supplies and (potentially) noise and ugliness. It'd be nice to avoid this as far as possible. Is there a nice enclosure that could house two disks of different sizes? Something that looks like an Iomega UltraMax or a Lacie Little Big Disk would look great on my desk. NAS, maybe? Stick everything on a big RAID disk (including internal Time Machine Backups, which will be small by comparison to my media collection so this isn't massively inefficient) with mirroring? Of course, this won't save me from accidentally deleting my media...

Cheaper is better, upgradable is also good but quality and reliability ultimately win.

I'm not currently interested in streaming (yet): I listen to my audio through a high quality DAC and headphones and I watch movies on my Mac.

Thanks.