The PS9200 used so called sequential sampling. That is why amount of necessary samples does not depend on acquisition window. That means that you can aquire 500 ps pulse with any of selected amount of samples (from 32 to 4 K).
In terms of the acquisition time (time that is necessary to acquire defined amount of samples). max sampling rate on the PS9200 is 200 kHz, or 5 us. If you want to acquire 1000 samles per acquisition cycle you need 5us * 1000 = 5ms + time necessary for interfacing with PC. In any case it is faster that 100 Hz.
Hope this helps.