The 1.0V supply is (on larger FPGAs) able to draw up
to 10A or so. You want a well implemented DC-DC (I'd
recommend one of the single chip buck converters out
there, like from TI or Intersil, LTC or maybe Maxim. You
sure do not want a linear regulator. And you had better
consider going bigger on the 5V feed because 1V@10A
at 100% efficient would account for all of your 5V, 2A.
I'm relatively confident that Xilinx has their own set of
recommendations for you, in app notes if not a fully
blessed go-buy-it partner solution.