Definitely upgrade the RAM. Also get at least two drives in RAID or ZFS or something so you can tolerate a failure. And keep backups too, if you can't afford to lose data.
In case of disk failure, simply redeploy and restore backups. Having an automated and fast redeployment procedure (and working backups) is a must-have, disk fault tolerance is not, IMHO (unless you have specific requirements).
I would defiantly not recommend you buying this. If you can you should get a ARM based SOC with sata drives. Its probably going to a bit more expensive but it will be way faster and efficient.
I would try to find something a bit newer. Core 2 Duos are really power hungry. Find one with an i5 processor and a T at the end of the number, like i5 3450T or something. This will be a little less performant but run at 30 watt max compared to the core 2 duos 150 watt. Fujitsu esprimo are also a good cheap option and both lenovo and Fujitsu offer rather tiny pcs that work excellent for severs.
Check to see how many SATA power connections are available. My Optiplex 3620 only has four and I wasn't confident that I could expand that without overwhelming the PSU. I bought a 24 to 8 pin adapter so I could use a normal non-proprietary power supply.
Consider those costs if you're thinking you might install a lot of drives.