Ive got the creative inspire 2.1's. SPeakers mounted behind the marquee, sub in the bottom rear of the cabinet. The sub's got an adjustable level control so I fired up asteroids, held down thrust, and turned the sub down when the cabinet stopped vibrating. It's stil la little heavy in some games but I typically play it loud anyway so it blends nicely, and for WinAmp Ive got the EQ tuned to drop some of the bass.
If the sub's not adjustable, there may be a software/driver way to adjust the sub output, otherwise yeah, you can try going out a hole in the back