Problem:
Is InterBase 4.2/5.0  for NT certified to run on NT/Alpha?

Solution:
InterBase for NT/Intel is not certified to run on NT/Alpha.  
There is a product from Digital Equipment Corporation 
called FX!32 which "gives Alpha computer systems and
 PCs full, high-performance x86 compatibility for 32-bit 
Windows and Windows NT applications".

Check out DEC's web site at:
http://www.service.digital.com/fx32/
http://www.windowsnt.digital.com/press/fx32.htm