A lot of people suggest using XModem, but this seems very hard to implement over serial...
I am sorry, but that is a funny statement. I take it that ZModem is out too...
Look, if you think you can get all 150kb without any issues, then, sure, good luck with that. Real world experience indicates otherwise. Some of us have worked with 300 baud over phonelines and a 150kb chunk of data was very unlikely to make it through the hours it could take for the transfer. Now with ZModem, you got auto-resume with the checksum capability of XModem.
Anyhow, take a little history excursion with XMODEM:
Even more sad, there is a library already...
http://code.google.com/p/arduino-xmodem/source/browse/#git%253Fstate%253Dclosed
and another...