Have you heard about WordWeb? It is a free software dictionary, thesaurus, and word finder. I love this program and have used it for a long, long time.
“WordWeb is a one-click English thesaurus and dictionary for Windows that can look up words in almost any program. It works off-line, but can also look up words in web references such as the Wikipedia encyclopedia.”
The thing I like best about it is the ability to use it, as it says,to look up words from within almost any program. There is no need to open up the WordWeb program. When I am writing, I just press the Ctrl key and right-click on whatever word I am working with. Up pops the WordWeb window. You can use it in email, while you are browsing the internet, any number of programs where you suddenly find the need to spell check, check the meaning of a word, or find a better word.
The tabs alongside the WordWeb tab are other places you can check if you are online. And the little plus sign you see in the lower white window below, when clicked, gives more and more choices the more times you click. Invaluable for writers looking for alternative words, and just handy for anyone needing a dictionary/thesaurus at their fingertips.