I'm afraid not. There's a spectrum of malware. The most malicious group
are removed by Microsoft's Malicious Software Removal Tool, which is part of
the monthly critical security patches--which are available today, by the
way--one critical patch for XP and the MRT.
Then there's a middle group, viruses--for these, you need an antivirus
application. There are several free ones available to individuals, so this
needn't be an expensive issue for the home users.
Then comes spyware and adware, which is what Microsoft Antispyware covers.
There's overlap among these groups--the lines are not perfectly clear--but
Microsoft Antispyware can't substitute for an antivirus on your machine.
