*bumped*
hi, just an update in case my experience helps anyone else. I used to run 4 webcams (all the same logitech 9000's) with various extensions: cat 5 to usb converter over 30 metres, an active repeater over 20 meters and good old straight into the computers usb's with the remaining 2. I had freezing problems and crashing quite a lot.
I stripped everything back to basics, flushed the registry settings with a file you can get on this forum, then reinstalled the program again and setup the 4 cams straight into the comp, all this running ok on my Core Duo 1.97 GHZ comp with 2gigs ram. My CPU averages between 40-60% - quite high but this is my dedicated security computer - used for nothing else.
I then set about attaching x3 usb active extender cables. 15, 20 & 25metres and ran the 4th cam straight into the comp, and that's where i'm up to now. I'm having the occasional freeze of the odd camera but am stretching things a little so it isn't too surprising. Getting rid of the Cat5 to USB extension cable seemed to help me and staying with active usb repeater cables.
For those that want to go the extra mile - you can setup repeating scheduled tasks which can run a batch file to restart Icamsource every few hours (or whenever you like really), this hopefully rectifies any occasional freezes or glitches that might occur, also the comp reboots itself once a day. All in all I can mostly leave the comp running without needing the monitor, and that's my (almost) maintenance free system. It's hard not to fiddle for better performance every now and then though!
regards. Sean
...forgot to say that am also using Dropbox to store files off site, and thanks to OUAntony for help with troubleshooting and suggestions.