The best multimedia OS is debated heavily. Windows is very good
because of the wide variety of applications, and hardware that is
available. Macs are good because of apples strong dedication to
hardware and software that work well with each other, Mac usually
achieves lower latencies than Windows can. BeOS was considered one
of the top multimedia OS's out there, unfortunately BeOS can no
longer support BeOS so most development has stopped, there are
people still using BeOS or Haiku, so this is a possiblity if your
hardware supports it. Thanks too the huge development base behind
Gnu-Linux, it is also a possibility. Gnu-Linux can achieve latencys
far lower than Windows and Mac can. Gnu-Linux can be hard to set up
for multimedia purpouses if one uses propietary components, such as
nVidia or ATI graphics cards, as these things often conflict with
the Real-Time patches in multimedia kernels. All in all... It
depends on the person, the hardware, and what specifically your
doing.