differences between ssrs reports and crystal reports

Question

hi....

as u all know about ssrs reports...

now i'm using the crystal reports 

and i want to go through ssrs reports

can anyone answer the following question. 

1)what is the need of ssrs...

2)and why we should use ssrs..,

3)what are the advantages

4)what are the disadvantages

5)how it will on work  webapplication..

6)how much loadtime it will take by server

7)whether it is a lightweight application or heavyweight..

8)what the problem that we face in future..

please help me  it'll be very helpfull for me