Minecraft requires minimal to no internet power other than on an SMP (multiplayer) sever. Minecraft does, however, require a rather suprising about of RAM, my machine runs on 2.5 GB with relativly no problems. But Minecraft is still a very low tasking game, just be careful on how much RAM you have tasked. Graphics card is minimal need, same with the processor. The other problem you may run into is the game saves for each of your 5 worlds can each run upwards from 5 MB and higher.