If you're looking for this information for tax purposes, almost any tax preparation software these days, like TurboTax, will assist you with amortizing loans. The key is to make sure that the software includes form 4562 - the info should be right on the box.

If you're looking for software to amortize independent of tax preparation, it can be a little more expensive since most of the products are targeted to tax and financial professionals as part of a bigger package. Consider one that's part of the TimeValue family like TValue5 or one of the LoanAmortizer products.