Thread Subject: Video Synchronization in Simulink

Hi,
I connected four web-cams to my PC by the USB port. My PC is an Intel Pentium D 3.2 Ghz with 2Ghz of RAM. When i try to visualize the four videos in Windows (in the same time) by using the camera's software the videos stream seems fluent, but if i try to acquire the four videos by using the image acquisition toolbox of Simulink the displayed videos are not fluent and seems not synchronized. The questions are:
1) Is it a problem of my PC or is it a Simulink limit?
2) Do i need dedicated hardware to acquire Synchronized videos in Simulink?
3) If i need dedicated hardware, are there some suggestions?

Furthermore, i need to process these synchronized videos (i'm working with a computer vision application and i have to do a silhouette extraction in each frames of each videos in parallel mode and reconstruct the 3D visual hull from these silhouettes),is it too pretentious do it with Simulink? (given the problem in the videos acquisition)

Thanks you a lot!!
Danilo