[dba-Tech] RAM Terminology

I'm shopping on eBay for some additional RAM for a computer that allows only
DDR1 (I can't afford a new motherboard as well). There's plenty to choose
from there and the prices are better than the local stores charge, but
before I take the leap, I'd like to clear up some terminology that I don't
understand:

- low-desity RAM (a few listings say this)
- high-density RAM (only one mentions this)
- (M368L2923DUN-C​CC) for
De<http://www.ebay.ca/itm/Samsung-1GB-DDR-PC3200-400MHz-M368L2923DUN-CCC-Desktop-RAM-/120783314737?pt=LH_DefaultDomain_2&hash=item1c1f3f1f31>sktop
RAM (only one mentions this)
- Non ECC (only a few mention this)
- CL3 (a few mention this)

I don't need a detailed thesis, just some guidelines. Is high-density better
than low, or vice-versa? If neither is mentioned, does that imply the rest
are "medium" density? The RAM I already have is 400Mz and nobody seems to
offer higher, so I'll stick with that.

TIA,
Arthur