well, after reading her website i think she just was suicidal but not homicidal. maybe all that she wanted was to die near columbine, where she was interested in. if she really wanted to go on a shooting spree, i guess she could easily do it outside the school after buying the gun.
someone on a other site seems to had contact with her in the past, he also posted some pictures of her (she was a cute girl btw). he said that he thinks she was just deepley depressed, she often talked about that. but she never said something violently or that she would harm other persons.
but we will never know.