Buy it again? Possibly. Mandrake is available to download as 2 ISO images from www.linux-mandrake.com (this is about 1.5GB to download so if you're on a modem don't bother ).

However, many people prefer different distros - SuSE is very good, as is RedHat, but the development stuff on that is a tad dodgy (non-compatible beta versions).

As for developing on Windows or Linux, it depends on what you're writing. It's a sore point on many sides.