OpenAL is pretty much the best thing you could use for cross-platform. If you are doing windows only, you can just use DirectSound if you prefer, but I woudn't try using much else unless you want headaches while trying to port your sound system over to new platforms. You'll just end up having to rewrite your games sound code for each platform.

Linux users shouldn't need user-friendliness, they're all super-geeks anyways. Just tell them what they need. Mac users will love you for using OpenAL and putting everything into one single bundle nicely/properly. Esp. those that like the new Launchpad for Lion.