BioGrids's preferred hardware vendor is ThinkMate and we have some recommended configurations for structural biology computing. Please feel free to contact us at firstname.lastname@example.org regarding upcoming hardware purchases if you have questions - we'd be happy to advise.
Any Apple machine can be a capable computer for structural biology. The basic Apple educational discount is available through their online web store, and your institution may have negotiated an even better deal with their Apple representative. BioGrids has several labs that run exclusively on Macs and OS X.