You can see an older post about this topic in my earlier post on this forum. I am working with these products and some others stuff of this kind for data modeling. Matlab is an expensive and powerfull tool that could be use for number crunching, rather that Mathematica is less expensive but you have less control on the computation. With Matlab you have more possilities for to link it with the web rather Mathematica, but Mathematica could do the job if your problem is not too big for computation. Also, for time series you have S-Plus that could do the job. Each of these product have time series libraries available (usually free, and some comercial package add-in).