Is the Crossover frequency option really important!

what are the crossover frequency ranges required in an Amp....how many ranges are available?......

i am actually looking at an HT cum Stereo setup for my room of size 12 x 10 height 10ft.earlier i had decided to go in for my hall n dining setup of size 18 x 13 height 20ft n adjoining dining of size 14 x 11 height 10ft,....but after feedback from all the people n visiting numerous places in bangalore,everyone suggested to go in for the floorstanding speakers for my hall n dining size!:( ...but the problem is my hall size. i donot have place for the floorstandings.so i thought i would set it up in my room of size 12 x 10 height 10ft.i wud generally be listening to music evryday and watching around 3-4 movies in a week.....

my budget is 40k including the desplay device(tv or Lcd panel).i was thinking for going in for a onkyo Ht-s570 HTIB.the amp with this package is got a crossover frequency adjustment for matching the frequency of the front speakers......i am even thinking of upgrading the front speakers to floorstandings in the future with this same amp.....my question is if i upgrade the front speakers in the future will i get a good setup/output with the crossover adjustment in this amp......can nybody give me the details of the crossovers how does it really help? in this way......i am planning to go in for a LCD monitor(17 or 19") so that i can connect an External TV tuner for TV viewing and this(LCD) will help me in attaching to a PC in the future......it wud be really great if u all could suggest on this and give ur feedback!

edges