A "server" is just a computer, the term is used pretty loosely. A REAL "server" would be a computer that has a very fast CPU, lots of ram, and usually no dedicated graphics card. If you really want to host a server for blockland 24/7 I would recommend using and older computer with nothing but the bare essentials installed, like the OS, firewall, antivirus software, and maybe a way of remotely controlling it (UVNC) so you done need to leave it hooked up to a monitor, keyboard, or mouse. I would guess that a computer with a 2 Ghz processor and 512-1024 Mb ram would be good enough to run a dedicated blockland server.