You have verified that your PC Rx side is working since you receive info from the Roomba. You can test the Tx by sending the command " 7 " and observe if your Roomba resets and sends the same startup info you have seen.
So does sending the command " 7 " work for Roombas that are Pre Oct. 2005 to verify that serial commumications are working. Also when you say command "7" do you mean ACSII 7, 0x07 or something different. BTW, I just purchased a Roomba scheduler to update the firmware on a Roomba Red 4100 and Discovery to get SCI ROI capibiliies which didn't work.
I saw you post regarding such not working eariler tonight. I will probably be renting a OSMO from you soon (I contacted you eariler this week). With the OSMO being so rare, I would think that someone would create a PC application that could do the same.