JJd210 you have a 1.5 ghz processor so here you go: www.newegg.com
Now to respectively address the OP.
With tekkit having 1000 ways to increase CPU load time, are you simply looking at the "Online players" or the actual console? Sometimes tekkit will crash with a high CPU load, will basically kick all players and present 0 errors.
Another thing could be "Chunk loaders". No players need to be online, but the server will mimic a player being online by keeping chunks loaded. As you can already assume, this would mean High CPU load time could occur even with 0 players online.
I would try to get your client to create a new map and see if the problem occurs.