at first thanks for your replies.
I haven´t been complete in the information I gave,
I wont use the arduino for just dimming a lamp, most importantly I need doing that wirelessly in some way.
being that with IR, or RF i don´t really know yet, maybe i´ll hook it up to an openwrt router. I haven´t really decided on this subject yet.
it´s a small domotica project.
about the current i dont really know, i haven´t found the datasheet on the ballast I use for now.
I know I cannot be more than 2A if i remember correctly and I believe it will allready work with very little current applied.
and what do you think about the not-using-pwm solution?
besides that i was thinking of maybe voltage dividing a 10v suppply with an R2R ladder a uln2803 and a shiftregister.
(or with a digital potmeter capable of taking a 10v load (suggestions are welcome)?)
while thinking about it yesterday i really kind of like the idea of not using pwm. if I also want to use IR and maybe an additional servo or stepper motor or so I might get in trouble with my timers.