I think I made it but cannot present results. Poser crashes in last stageof rendering :D
I love it.
Anyway I've seen 75% of picture. I used Daz freebies prop "opera stage", 6 infinite lights "no shadows" - up, down, left, right, front, back with 10% intensivity and 0 atmosphere str. Spot light has 0,1 atm str vs 0,01 default - looks exactly like light beam on the stage. I think I'll change infinity lights to point what let me keep everythink except scene in the dark.

Morkonan - I thought about transparent prop (I used it when rendered shower drops) but prop does not look good in area where it crossing another surface (in this cause stage's floor). I could not find any tutorial here but I hope I do not ned it now ;)

Thanks all. You really help. Now I'm turning off services in Windows to more memory. I'm happy that I'm using XP not Vista.