I've been a long running fan of Alpha hardware and will never forgive the Q for scuttling it to schmooze up to Intel. Disgusting...
There is an AlphaNT version of IE 5 and as I recall an upgrade to 5.01.
You should be able to get 5.0 here:
http://microsoft.com/msdownload/iebuild/ie5_alpha/en/ie5_alpha.htm?FinishURL=%2Fdownloads%2Frelease%2Easp%3FReleaseID%3D10314%26area%3Dsearch%26ordinal%3D39%26redirect%3Dno
(delete spaces in the URL)
If that doesn't work, go here:
http://www.microsoft.com/downloads/search.asp?
Choose OS Windows NT (Alpha) and all releases. You'll see the links for 5.0 and the upgrades.
For other alpha software (and info) take a look here:
www.alphant.com
ftp://dutlbcz.lr.tudelft.nl/alphant/
Good luck...hope this helps!