I load my precision ammo on a 550b fwiw, and have compared ammo made on both the 550 and stuff that was made on my rockchucker.....While I agree you can always find a use for the rockchucker, you can get away with a 550 as a first press....
I will also suggest that you start with a single stage press.
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See a great comparison of progressive presses http://www.canadiangunnutz.com/forum/showthread.php?t=127691&highlight=dillon+lee+hornady
Get a single stage for your first press, ESPECIALLY if you're completely new to the concept of reloading. It's not rocket science, but a single stage will give you much finer control over each reloading stage, and probably a better understanding of the various steps.
Also a single stage is your best bet if you plan on loading for a precision bolt gun (as opposed to higher volume handgun or 'tactical' rifles)