The dumb questions are those you dont ask... usually..
the datastores are where you store the "virtual disk images" for any guest OS you have.
you do not need to buy SSD's. in most cases you can just use a mechanical drive depending on your use.
I chose SSD's for pure performance. (I also have a ZFS storage array on the server for more datastore storage, thats a bit advanced for most people)
It is usually recommended that you use a "raid array" on a SANs or NAS and have ESXi map to it via NFS or iSCSI for the datastore.
I chose to keep it more of an all-in-one build. it is much simpler for my build. plus it is one less server to have on and cheaper both parts and electricity.
if you only plan to have unraid and maybe a few windows/*nix guests. a 120-250GB mechanical drive might be all you need.
Thanks for this. As the WHS will only have mymovies, itunes server and thats probably about it on it I guess a 128GBish SSD will do just fine, and have the speed to boot.
Now I just need to stomach buying all the stuff, I don't suppose anyone has the winning lotto numbers they wish to share?
Regards.