I came across this in a desperate google search to see if anyone else is having basic connectivity problems with the create as well. Sorry if I'm ressurecting a dead thread but I was wondering if you ever resolved this.
I tried following the manual and using their http://realterm.sourceforge.net
program, and I attach the create to my pc via a serial port but I get absolutely nothing (no incoming data and any commands I send seem to go into the abyss.)
I seem to manage to get somekind of response by sending the 128 opcode sometimes (the roomba beeps) but thats about it, all the other opcodes are absolutely ignored.
I phoned the irobot tech support and they seemed more than useless, telling me its probably because I am using Windows 7 and I should be using Windows XP as thats what the Create was designed for... though I fail to see how that would change anything, as a serial port is still just a serial port....