Upgrading my old crusty NAS

So I have a NAS that's about 4-5 years old, a Thecus N5200 5-bay RAID NAS.  The problem with old technology is that even if something works, the manufacturer starts to neglect it.  I originally stocked the NAS with 5 750gb drives in RAID 5 for 3TB total storage.  When I started collecting vinyl and other high res audio, I ran out of space and added a 2TB external drive to it.  It's almost full, and that's without the DVD rips I'm working on.

Today you can get a 2TB drive for $80, so it's time to upgrade (which would give me 8TB in a 5 drive array).  The problem is the drives are not "officially" supported -- but the reality of what that means is that Thecus can't be bothered to test them.  They should work.  Gulp.

I took the NAS apart to dust it out.  I've cleaned it externally a few times, but when I cracked the case open, good god was it filthy.  Inches of caked on crap in places.  I'm amazed it didn't short out.

While I was in there, I noticed the old 184-pin DIMM was only 256MB and I'm going to upgrade it to 1GB.  Time to back up and prepare for NAS 2.0 (and pray it works).