I fell out with Norton when it changed a load of registry settings and messed up networking - it needed a special removal utility. I believe the latest versions are better, but in Windows I use AVG anti-virus and AVG anti-spyware.
Tiscali has filters which stop most of the spam, and you can also set your own filters to delete at source - so no need to download. And then there are spam filters in Thunderbird.
Despite all this, some still gets through and it seems to be getting worse.
