Max, in addition to the OED, I have MWCD-10 (it's exactly the same data base as that available at http://www.m-w.com/ but, of course, is 'browsable' by headword) and AHD on CD-ROM. of these two the AHD has a better search function and audio pronunciation (the MW search is weak!), but MW has the better wordlist and is generally more user friendly. I can give more detail via private if you'd like.