Sound Forge for audio editing, Cool edit 96 is handy for the save region feature.

Cubase and Nuendo if you want to make your own record. Some people get on better with Logic audio, but it's pretty steep to learn. If your PC will cope get "Pro Tools Free" of digidesign.com or whatever it is. It's 8 track, and quite limited but the quality is good.

for notation, get Sibelius if you can afford it. Nothing else comes close. I'd recommend personal composer for windows if you want something at the budget end.

Theres a lot of Warez out there, if your conscience will allow... Not sure that I approve, but then again, we've all taped stuff off the radio...

alt.binaries.sounds.utilities is a good starting place.

Of course,what you do there is entirely up to you.

My view is if you find you use something a lot, go and buy it.

Cheers, Jon