It depends. If you're just rocking a two-speaker setup that you use to play some of your favorite tunes, probably not. If you're looking to upgrade to a multi-speaker setup, you might consider investing in a discrete card for the additional ports or software features it provides. If your motherboard-based audio can't simulate a 5.1 surround out of a two-channel audio file, that could be a deal-breaking factor for you. And if you're intending on making your desktop PC the centerpiece of your home theater setup, a head-nod for more advanced connections that fit your receiver or speakers' inputs might be in order.

Will a discrete sound card automatically make your tunes sound better versus a motherboard-based chip? No. Will you gain a huge boost in a game's frame rates by offloading sound processing to a separate device? Nothing noticeable. What you will gain is the ability to do more with your system, but the utility is going to depend on your acoustical needs. Be sure to keep your use case in mind when you're shopping for a new desktop.