solution is easy ......... just use osx then 🙂
sorry i know you gamers want sound too , as i did hear the sound of the imac 27 " and i somehow think there is no improvement in sound since the iMac g5
so just get some bose companion 5 and all sorted then
just bought some for my iMac g3 , and i can recommend the bose companion 5, they offer really great sound 🙂