Parallels is allowing you to run Windows apps alongside Apple apps.
Boot Camp just installs Windows drivers and partitions your harddrive, so you will just run Windows natively on your MacBook (Pro), it can be `just another Windows laptop'. You get the performance you'd expect from a 2+ GHz Core 2 Duo
Parallels is an emulation which is slower than running Windows directly. If I were you, I'd just go for it. In the worst case, you boot into your favorite flavor of Windows (XP Pro or Vista Home Premium Ultra Edition) and launch Flash under Windows.