I think it's worth it, as it's cheap. It depends on how you use your computer. You would be better off buying a nice new graphics card, though, no matter what. FUN FUN FUN!!!
As much FS is concerned, the problem of decaying performances because of sound is not due to a videocard issue. Most, if not all, the motherboard integrated soundchips are scaled-down, cheap soundchips from soundcard with no DSP, this makes so that processing sounds require part of the main CPU power to work, and if the sound drivers are not up to a good work, the processing of sounds can cut into the general performances something fierce.
In a good PCI soundcard, regardless by drivers (which can give other kind of problems, though, if not adequate) the soundchip contains forcibly a DSP that processes the sounds all of its own, the only thing the main CPU have to do is to pass the parameters (and it's a way lighter work than processing the sound).
Hence, changing videocard when you have performance problems due to integrated soundcard is not a solution.
There's but one real cure for human stupidity. It's called DEATH.
At the moment mourning the assassination of sarcasm and irony for the good of the "higher".
Proud FSIX user. Active user of FS98, X-plane and novic