Thanks all for the quick responses.
I will try it out and post back on how it turned out.
I do understand that the best way to do things is to get a used later model Roomba. However the challenge is even bigger with the older roomba and the immediate reason for doing this setup is that I want to use components that I already have than to buy other stuff. Of course if this fails, then I will be looking at going the route of the 4xxx or 5xxxx from ebay
Just for perspective this is the big picture plan:
I plan to use the the Roomba+Foscam device to monitor my home over the internet when I am away and there is no one at home - not just for intruders, but for the state of appliances, visible leaks etc.
I plan to use this solar powered rechargeable battery pack for the foscam ( http://www.gomadic.com/foscam-fi8908w-s ... ry-charger
The default "resting" place for the contraption will be next to a window where there is plenty of sunlight most of the day. So this will keep the foscam charged and always-on. (of course provided its not a rainy day - and even if it had a dark day the next good sunlight day should bring it back).
Once every 2-3 days, when I login remotely, I plan to use the foscam to turn on the roomba and take it around for a spin of the home to ensure everything is on order. It will then be driven back to its resting place for charging.
Since the roomba is not going to powered on for long periods of time and the always-on foscam does not take power from the roomba's battery, I am hoping that I can keep the roomba battery going for a few weeks that I will be away.
Based on the information from Gordon, it appears that the Virtual Wall sensor on the Roomba requires a specific type of IR signal and it may not read the IR signal that the foscam puts out....buts thats ok, I have a good working virtual wall itself (that came with the Roomba) which I can place on top of the Roomba pointing at a slight downward angle and maybe powered from the Roomba itself. Then the beam from the VW could be blocked selectively and delicately by the foscam's circular motion (or reflected from a mirror attached on the foscam) according to how the Roomba should move - not easy setup, but I think doable. Agreed that it is not going to go in a straight line, but even if it does a few semi-circles to go from room A to room B, that would be sufficient.