I have been informed in advance that there will be a large meeting with 75 people with laptop in one auditorium. This auditorium has 2 Cisco 1130. Will this be enough to support this number of laptop at same time? Do I need to add more access points?
Rule of thumb is that you don't want more that 25 clients per AP but this really depends on the type of traffic. For instance you don't want more than 7 active voice calls per AP at a time. So it really depends on the type of traffic.
In general I would say if you can add another AP I would. Also if these are dual-radio AP's that would help too. Hopefully the clients would load-balance across the radios.