It's sort of an Office for developers. The "professional" v6 package comes with Basic, C++, FoxPro and InterDev plus assorted utilities. The "enterprise" edition comes with additional components for database development and other nice stuff like a cut-down version of Rational Rose for use with Visual Basic.
For the OP, if you're a student get an academic license. It's dirt-cheap and you also get some bonuses like service packs and MSDN CDs.
EDIT: At least some of the versions also come with SourceSafe, which is nice if you trust it.