What are must have programs for musicians and studio's etc.

The new Logic Studio R-O-X

The majority of professional studios use Apple Computers Loaded With Pro-Tools. This is DAW (Digiatal Audio Workstation) is also the most expensize out there. The limiations of this sofware is that it will only work with pro-tools hard ware which is also very pricey.

The software alot of studios use instead is Digital Perfomer (DP) made by Motu (Mark of the Unicorn).

Along with this software there are ton of fun, productive apps that can be used to enhance your studio.

Propellerheads inc. Make a product called Reason. Reason is a midi controlled sequencer for live and studio.

So a list of thing that I use are.
Pro Tools
Digital Performer (MAC)
Steinberg Cubase SX (PC and MAC)
Propellerheads Reason (Mac and PC)
Waves Plugins (Compression, Reverbs etc…)
Native Instrument Kontakt (Sampler Software)

Theres also a ton plugins.

Check out this website and get their free magazine.

http://www.tapeop.com/

^ good list ^

add:
Ableton Live
Guitar Rig

http://making-music.blogspot.com/2006/01/big-list-of-free-music-making-software.html

“acid” is a pretty good program
my friend made a song with that… i dont have any details

Another vote for the Logic line (whichever level is appropriate for your needs).