When it comes down to it theres no one program that is the be all end all. I use
-hoster (clean the host file right of the bat and mark it read only just cuz)
-Adaware (update full system scan) - If I'm working on a slower/old machine I use Ewido as it seems to be lighter and less of a load on the machine. but hate the noise if uses when find somehting.
-housecall.trendmicro.com (gets rid of pettie viruses)
-autoruns ( if hijack and msconfig had a baby this would be it) used to clean startup and such.
-hijackthis (usually just run this once everything is clean because I've only been using autoruns for a short time and have been using HJT forever and want to make sure it does the same job)

that will usuallly do it, if theres problems I use
-processxp to suspend the process then kill the regfiles (if dlls are locked into winlogon )
-killbox to delete dlls on reboot. works for everything but winlogon + dlls as they start before
-nod32 trial (viruses/trojans/backdoors/general maleware)
-thecleaner trial (viruses/trojans/backdoors/general maleware)

Also I use firefox untill the spyware guys figure out howto exploit the hell outta that, its bound to happen sooner then later.