^^ For all purposes, you can use that software
Vocab building is actually pretty easy, if you're training for gre/toefl/gmat/ielts you can do 5+ words a day. For a school student or anyone with average english knowledge 1 word a day would suffice. But one advice common to everyone is, read. You can read anything like novels, magazines, newspapers but do it in front of the comp since you can look those hard-sounding words up at dictionary.com or get a dictionary software(I use merriam-webster's collegiate dictionary software) Take this from a person who does vocab training when bored.