If you're still using those cheapo speakers you bought from Office Depot for $20, it's time to upgrade. Luckily, it's not that expensive, because today, powered Klipsch speakers are 50 percent off and a Polk subwoofer is 62 percent off.
Today, Amazon is selling Klipsch R-15PM powered monitors for just $259 (normally they are $500). These speakers are powered, meaning that you don't need an additional amplifier to push them. You can simply plug them in and get great sound instantly. If you've got some more money to burn, may I suggest you also pair these with a Polk PSW10 10-inch sub. For just $89 more (normally $240), you are going to get incredibly full sound for less than $400 total. You won't regret it.
If you want to go down the rabbit hole of computer audio, check out an article I wrote last year about our current audio setup.