Recording device for sound across on the street

There has been people harrassing me across the street, I think they are probably some young people in one of the houses on the other side of te street. I need to have evidence for me to report to the authority, so I am thinking of recording their shoutings and taunting towards me by a recording device. I am not sure which device is the best for this task, my own nokia mobile has a recoridng fucntion but it sucks it doesnt really record anything. Any advices? Thanks.

[ol]
[li]Check your state’s laws about recording people without their knowledge/permission.[/li][li]Buy a microphone for you computer and record it with the mic sitting in an open window.[/li][li]If legal under #1, call the police to report them.[/li][/ol]