I am going to assume this a purely pc based set-up due to the location of the thread. A studio monitor is designed to have a flat frequency response, this will do nothing other than give a transparent representation of what you are playing. It should not sound bad or not true, more often it may sound a little different at first, your ears will adjust to the subtle differences.
For example I have an off the shelf 5.1 system for my tv room that cost no more than £100, its ok at best but its certainly muddy with inflated bass due to poor speakers and a huge flabby sub, my wife and kids would say it sounds fine. Move to my office I have my recording gear with some ADAM A7x and a pair of KRK Rokit 6's. I originally had the ADAMs to work with and was happy as hell with them, then I bought the KRKs so I had a second set of monitors to compare when playing around with recordings. The simple truth now is (and I hate to admit it) is the main speakers I use now are the cheaper KRK's, as they are less fatiguing when recording, the ADAMs are the alternative speaker which I use as a comparison. I watch films, play games and record all on a set of cheep KRK's, and my expensive ADAM's sit almost redundant for days on end.
Dont put too much stock in the label of studio monitor as at this level they are hardly on the scale of any studio other than a home artist or a hobbyist like myself. You can use digital EQ, its not against the law. I am sure you wont regret the purchase, at worst its going to open your eyes to how weird/bad TV and multimedia speakers are.
One more thing, you will probably find the smaller speakers with the sub a better option if budget allows.