It's the smallest form factor you have ever seen, and it's hard to believe an entire PC is in there. You can insert two SO-DIMM memory modules and one 2.5" HDD/SSD.
We installed two GB of OCZ PC-6400 (800 MHz) in a dual-channel configuration. We have nice low latency CAS 5 DIMMs, these are SODIMMs, similar to what you use inside a laptop.
For storage we went all the way, you can insert a quiet 2.5" HDD of course, but we have a couple of SSDs laying around, and especially with a platform that is not the fastest in the world, here's where you can gain performance. This is a Sandforce 1200 based 100 GB SSD.
We close up the lid again, screw on the wireless antenna ... and we're ready to go ... oh wait, no DVD-ROM, how are we going to get an operating system like Windows on there ? Well, next page please.