d3drs_multisampleantialias: check for it?

[Devils Cry]

Hi again... :/ ^^

So im now moving for the multisampleantialias call... ive found the
gl_multisample_arb function to be matching, so far, so good. Now while
googling for it i only found code examples which check whether
multisampling is supported before it is activated. My question: do i
need this? I found no other call in the d3d8lib which asks for its
extension the way i found it
(http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=46). Theres also
another problem: the multisampling has to be turned off after its done,
turned on again if something is drawn and after this turned off again
(at least i understood it that way...). Is it enough to simply turn it
on? And if not, how should i do this???

Thx in advance
Nikolas