Go through these links too... they might be useful to you.
http://arduino.cc/forum/index.php/topic,151021.0.html
http://arduino.cc/forum/index.php/topic,150989.0.html
Initially I was facing the same issue of bootloading. I had only a Usbasp programmer & Arduino IDE. The issue is solved not. The solution is in the abovementioned threads.
cheers
