sorry to say but those speakers look like junk to me yebol. i wouldnt pay $500 for any 2.1 computer speaker system. if you look at a review it seems that the output isnt bad but its not worth the price.
you dont have to spend your entire budget. i only stated that you had the option of going with such a setup because of your larger budget.
honestly there is a broad range of prices and quality to components you can buy.
for instance you could get a pair of bookshelf speakers like these
http/store.sony.com/p/SS-B1000/en/p/SSB1000 for $70/pair or these
http/store.sony.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=8198552921665089277 for $200/pair.
i can personally attest that the bass levels in the sony floorstanders are quite good and dont need a subwoofer. while perhaps not the best speakers in the world they will not break the bank.
you can get a stereo amplifier for $100-200.
of course you could get a better buy (i've seen amps for $60 and sony tower speakers for $110/pair) but just estimating high.
instead of an amp you could always get a cheap receiver if you plan on connecting up multiple inputs. for example you could connect your pc, consoles or other such devices up. a receiver also nets you an am/fm tuner and a few other options but for pc use only an amplifer would work perfectly fine and is cheaper (since it is simpler).
my setup is in a 12x14 room (3.5x4.2m) and inside i use a 450w sub, 5.0 satelite speaker set and receiver. it works out well however the sub is a bit overpowering so i keep it at medium or lower. satelite speakers are generally lower powered and are only good for mids and highs so you need a subwoofer. the larger bookshelf and tower speakers have subwoofers built in so a seperate sub is optional and not required. i went with a high quality set ($550 for just the 5.0 sat speakers) and even this is considered low end.
in general... home theater speakers will sound way better than pc speakers but you may have to spend a bit more to get them (but your budget of $700 is fine for this). i stepped up from pc speakers years ago and havent looked back.
there are other brands besides sony which you may want to look at but i'm not an audio guru. i've personally used the sony tower speakers so can say they are a great deal for the money but besides that i can only offer some general advice.
perhaps one of the resident audiophiles can help out on here if you choose to go the home theater speaker route and give you more choices.