Guild Wars 2

I just got fraps for recording, would anyone know a decent editing software for AVI files?

Features I’m after:

Cropping, slowmo/fast forward effects and option of adding own music.

I use windows 8.1

Does it have to be free? If not the Sony Vegas Platinum or Suite are great. Vegas Pro is even better but with a ludicrous pricetag that only professional video editors should bother with.

Sony Vegas is very good. Many features and it has built in tutorial.
Check out comparison http://www.sonycreativesoftware.com/moviestudio/compare

sony vegas is a good program, but they call everything else something different from industry norms, just to be different. good keyboard/mouse hot keys that make sense.

avid pinnacle is an easy to use program and has the features you are looking for. export options here are more limited without additional plugins.

adobe premiere of course can do almost anything, but it has a steep learning curve.

avoid anything that claims to be free and easy to use. it wont have half the features you want.