[Sunny Thaper]

If you are looking at a professional product I HIGHLY HIGHLY suggest Propellerheads Reason 2.0. I might have spelt that wrong but the address should be www.propellerheads.se. It is the greatest synth music creation software ever. I can send you a couple of samples that I have and it actually comes with loads of them too so learning isn't much of a problem. The best part is you don't have to be a musician which I am DEFINATELY not to create good quality music. Plus the file sizes are less than 100k most of the time so size and computer performance is not a problem.

If you are looking for something more catered to only loops, Acid Pro is a great solution. That is what we used for our animation last year. We used it for not only music but also sound effects and dialogue. You can get suprisingly accurite.

Now if you are looking for something to make you music really freaking quickly without you learning anything, and this is a product I only endorse for those of you that are basically thinking of no sound as your only option, I suggest Mix Man Studio. It's not by any means a great piece of software but you can get some really decent music in no time at all. If my ears served me correctly, a couple teams last year used this program. It can actually get pretty fun but once again it is only for quick dirty music, nothing professional.