Well, since I'm a new composer here, I'll add my 2 cents:
I use Cakewalk Sonar x1 Producer. For years I used their Cakewalk's Homestudio 2, and it was great for me; that as an upgrade from an old midi editor called WinJammer Shareware (the slickest little midi editor I ever found on the internet, Winjammer taught me the basics of music... ). Unfortunately, I lost my install disc for Homestudio 2 and had to upgrade. Happily enough though, the upgrade to Sonar X1 Producer was worth it, the program is slick, and has great sample/ digital instrument quality packaged with it. I was so used to my old shortcuts and workflow though, learning the new program was kinda difficult.
To edit audio files I'm in love with Cool Edit Pro 2, which I guess was purchased by Adobe years ago and became Audition? In any case, it's my favorite simple tool for cleaning up beginnings, endings, post amplification/fading, converting to MP3,etc, also for cleaning up sfx. Somehow I got it to work today on Windows 7, when I first installed it on my new computer the audio engine crashed, but it works suddenly! (YAY!) I also still use Winamp to dump to Wav/Mp3 or to add ID3 tags when I need a tool that's old and reliable.
(Note: to run Sonar x1, I purchased a simple usb soundcard the cakewalk UA-1G. No onboard MIDI in/outs, but works great with my system, little to no latency. However, the headphones monitor has a significant amount of background noise/static that actually sparks my ears a little, for some reason).