Probability System of four independent components

Here is a probability system

http://i140.photobucket.com/albums/r...se78/asasd.jpg

The probability of failure of #1=0.1, #2=0.2,#3=0.3,#4=0.4

Now im trying to find the probability that the system works..

I so far have 1∩(2U4)∩3 which seems right but I dont know what numbers to plug in and whether to add or multiply

Also, I need to find the prob. that at most 3 events of these components work.

Then, using conditional prob. I can't seem to find the prob. that the system works given that at most 3 of the components work..

Im so lost