I would recommend a license from Stopzilla. One warning though: it can break one or two applications in the process, but I know other applications which have done the same. It's really, really good at detecting and finding trojans.
For anti-virus: go for a 30 day license from Sophos and keep on using the free license by constantly registering at their homepage once a month. It's not enough, so combine it with anti-virus through active-x plugins too. You can combine E-SET and PANDA.
For constant anti-spyware protection: CounterSpy. It has never caused anything to brake in my system so far and don't slow down the system very much, either. It has a pretty fast scanner, I think it's good.
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/Bear Spirit, undiagnosed: AvPD and SPD