Spyware Doctor 6.1.0.447
Release Date: July 28, 2009
Operating System: Designed for Windows® Vista™ 64-bit SP1, Vista™ 32-bit, XP (Home and Professional Editions) and 2000.
http://www.pctools.com/spyware-doctor/

Windows® 98 use 4.1.0.1
http://www.pctools.com/spyware-doctor/version4/