Software you can trust - and it's free
There are a lot of websites offering 'free downloads' of software for Windows nowadays. A lot offer you what's called 'shareware' or 'crippledware'; you install it and then some important features (like, oh, say, saving) don't work until you upgrade by buying the next version. Some, even, come with 'phone home' programs which report on your use of the Internet.
Not to say all sites are bad; NoNags.com and FreewareGenius.com screen for such nonsense. But how do you really know what you download is good?
Answer: Use open source programs, where the programmers reveal all the programming files which went into the program. Other programmers therefore can see what it does, and they will (and have) scream bloody murder if there's badness involved.
http://osswin.sourceforge.net/ has a list pre-screened for Windows. If you don't find it there, look elsewhere in Sourceforge, part of the ThinkGeek media empire which includes the well-known Slashdot IT/Science news website.
Click on the blue [Filters] button, then in the spin box which appears, choose Operating Systems. From Operating Systems, choose 32-bit Windows (your variety), 64-bit Windows (if you have that flavor) or whatever OS you have.
Then go back to the filter line, select Exclude, Development Status, and choose Planning. Repeat the Exclusion on Development Status for Pre-alpha, Alpha and Beta (unless you are feeling adventurous).
A menu at left allows you to focus further on the category of program you're looking for. If you're looking for an accounting program, look under Databases (for all accounting programs rely on a database).