you arent going to get a z5500 for $200 unless you come across a hell of a deal.
that said, the z5500 is the best logitech speakers they have made so far.
you can find that set for $300-400 normally which really isnt terrible.
if you must adhere to the budget then get a lower end set. the subwoofers are typically more than powerfull enough even in the $200 5.1 sets.
if you want something even more powerful then you would be better off getting some nice big tower speakers and an amp and hooking that up to the pc. or getting some bookshelf speakers (2.0) and pair it with a sub and amp.
some large tower speakers can shake the walls in a room without a sub... and if you get smaller speakers the subwoofers you can buy are way more...