What sound card are you using and are you talking about EAX Effects ? (that gives the boom when playing old-games which are EAX-enabled)

Some onboard audio card's "boom boom" may have been stripped off in Vista. Especially Realtek onboard (The control panel for XP has a lot more functions as opposed to the one in Vista)

So wait , you're using onboard sound card right now ?

Its better to opt for Creative X-Fi (like the one I am using now) for optimal sound quality. Their drivers work well with Vista. Pair it together with ffdshow (to trans-code and to output to 5.1)

To tell you the truth , onboard audio with Vista sucks. Maybe they give you a bit more options on XP but on Vista you are better with Creative's Sound cards !

Try to run ffdshow first. Then tweak with it to get the best sound quality if it works. Alternatively you may want to check out Garage Sales. You can get XFi cards for like RM 150+ (these are way better then Audigy Value)