Can't find any other info on that server, but going off what you said...
Minecraft only supports 1 CPU, so the 2nd is useless for it.
Those CPU's only have 1 core each, and while MC servers do only use one core (AFAIK), the rest of the system will also have to use that core, and that won't be good for performance.
The CPU's run at 2.667 GHZ, which is alright, and if this was a dual/quad core, I'd say it would be fine. But because everything would need to run off a single core, I don't think it would do very well.
4gb ram is okay for a small MC server (dedicate 3gb, leave 1 for system, or 3.5 and .5 if you run a lightweight Linux distro), but since the rest of the server is old, I'm willing to bet the ram is slow, so i'm not sure about it.
anything it can be used for at all? if the server has two processors can one be used for the system while the other is only used for the minecraft server?