Honestly? There are lots of different tools you can use to make music, but what you can use depends on your budget.
Free vs Paid
The universal question is whether you are willing to pay for something or if you need something free to due financial constraints. There are some free DAWs (Digital Audio Workstations) that are free that can help you get started. LMMS is one of them, but I recently tried it to see how it fared against SONAR X3 and honestly, if it could use the Play VST, it might have been really nice, but sadly, didn't want to load it at all. Still, there are other free and lightweight VSTs that it will load along with SF2 and SFZ options, which is good. One library, which I think is now discontinued, is the Sonatina Symphonic Library, but there are downloads of it available in other places. It's an orchestral library that was made in the SFZ format. There are lots of other tools and instruments that are free for use that you can find littered all over the internet. Check out KVR sometime to find some nice stuff or do a Google search for free instrument VSTs or DAWs.
As for paid, lots of people love the SONAR and Ableton programs on Windows and ProTools on Mac. I personally use SONAR with the Play library from EastWest. I have some other ones available, but the Play library is huge and I had to set them aside for this. I've always wanted the chance to use the libraries from them, but they were always out of my reach. Since they came out with the Composer Cloud services, I have been able to use them and it's really nice. Those are the DAWs and for instruments, Play is the way to go if you're on a tight budget. You get all their instruments if you go with at least their gold package and it's $30 a month. Quite the steal. There are many others, but you'll be paying large amounts of money for them. Of course, they are worth the money, but sometimes budgets don't allow for much more than basic stuff. If you can afford it, try out the Cinesamples or Orchestral Tools libraries, but keep in mind that they require Kontakt to be used. If you're feeling REALLY gutsy and have a good amount of money, go for the Vienna Symphonic Orchestra library. Probably one of the best out there with a feature-rich toolset, HUGE library with almost ever imaginable articulation available to you and great support.
Quick run down. Trust me, I could have gone on about this for a LONG time, pointing out pros, cons and huge lists of programs and instruments, my experiences with them and so on, but it's late and this is a really quick post to show you what most people use. By the way, if you're also doing non-orchestral, check out Impact Soundworks for electric guitars, bass and a drum set, Toontrack for a really high quality drumkit called EZDrummer and EastWest has some ethnic and electronic instruments in their collection, which is included in the gold package of the cloud service, that you might find useful.
If you're new to making music you may find this link from my signature helpful. But, if you do have music making experience and the budget for professional software, then the answer would be much different. Could you describe the types of music you're wanting to make? If you don't have a lot fo experience I definitely recommend toying around with free DAWs and samples for awhile before purchasing anything. Music software can get uber expensive.
The other day I posted a merchant airship tileset and said it was overflow from my Advent Calendar. @Avery said something like "that's one way to flex!" Well, this morning I woke up and realized THAT I MISCOUNTED AND AM SHORT BY ONE DAY. My face and palm are now perfectly fused together.