Thanks for the feedback. The comment re. TTL helped a lot as it gave me something else to research and learn.
I also read through all of the Virtual Wire source, and it would not be hard to port the logic over to another language or app that was receiving signals.
To complicate things a bit, I purchased an rf receiver/transmitter pair that uses encoding. I am not familiar with the encoder/decoder chip, but it sounds like something fairly standard. I don't think this would interfere is I was to use Virtual Wire, but it I think it implies if I was to use multiple transmitters, I would have to make sure they all use this encoding.
Since I want to have one receiver and multiple transmitters, sending temperature readings, I need to make sure all transmitters work with the receiver.
Does anyone have any thoughts or suggestions on these encoding chips? I am tempted to try this out as an exercise, but then move to one of the low cost rf's I've seen mentioned and use Virtual Wire.
Thanks for the help.