New guy, new rifle?

[Sturmgeschutz]

I'm a very inexperienced hunter, but at some point I would like to go on an African hunt (I'm thinking in about the 15 year timeframe). I have been looking around on the net quite a bit, and I am thinking of picking up a rifle that would be suitable for African dangerous game. I plan on doing quite a bit of hunting with it in the States and Canada before I head across the water to do the big hunt, so I am interested in getting a robust rifle.

As for manufacturer, I have heard good things about the CZ-550 series. I have decided that whatever rifle I get, it will have a mauser-style giant claw extractor. I have looked around, and the CZ rifles, and Charles Daly rifles have caught my eye.

The biggest problem I am having is on deciding the caliber. I see quite a bit of rift between the .416 crowd and the .458 crowd. Basically, the biggest question I have, is which of the 3 big cartridges should I go for? 416 Rigby/458WMag/458Lott...

Basically I was wanting some constructive criticism of a guy that is planning on buying a CZ550 in 458 WMag.

I know I'll get asked, but I don't know what my target game will be. Going on an African hunt is way out there for me right now, but I would like to get accustomed to hunting with a big-bore, hard hitting rifle, and use it for a while so that I am very comfortable with it by the time I get the opportunity to go on an African hunt. I have read around and seen that these 3 cartridges seem to be the failsafe cartridges for pretty much any game in Africa, and that is why I am considering them.

Any thoughts on this would be appreciated. Thanks in advance.