[Spktyr]

http://www.oup.co.uk/episbn/0-19-923176-1?view=ask

Supported operated systems: Microsoft® Windows® Vista, Windows 2000, Windows XP, Windows Server 2003, Mac OS X 10.4.x or later (PowerPC or Intel). Requires Intel® Pentium® II 450MHz or faster processor or equivalent (Windows), or PowerPC® G3 500MHz, Intel Core Duo 1.83GHz, or faster processor (Mac), and 128MB of RAM

Try contacting them, they may let you crossgrade for little or nothing.

[ALPAPilot]

I have the full OED on CD-ROM, and that does not run on MAC.

Available in a single-user PC version only. No network version available. No Mac version available. For information on the online version, please contact worldinfo@oed.com or visit www.oed.com