I play Minecraft pretty frequently on every platform it's available on. I think what would be best would be to beef up the processor a little, go for a decent dual core Intel or a triple core AMD, get around 6GB of 1600Mhz and up RAM, and just for convenience's sake, grab a OK Radeon GPU. There's no need for 8GB of RAM for Minecraft when it can be better spent towards the CPU. The only instance that much RAM could be more helpful would be if he's going to run a medium to large sized server, or multiple medium sized ones. The GPU isn't exactly a must considering the game operates on Java and mostly eats the CPU up anyway, but just to have one for all intents and purposes, would be nice. Personally, on that budget, I'd grab him a decent AMD triple core, 6GB of 1600Mhz RAM and a Radeon 6750 or something along those lines. That's just what I would build based on the needs and budget, but ultimately it's up to you and him. Hope I was of some help.