Many Internet users understand just how annoying and increasingly prolific spyware can be. Even if you use the Firefox browser and antivirus software, programs such as Ad-aware SE Personal Edition, Spybot Search & Destroy or even Microsoft's new AntiSpyware Beta are still required to maintain a clean system. So if such software does a respectable job, at no cost, the question is: does Spyware Doctor offer enough to justify its small fee?

Spyware Doctor (SD) is an adware and spyware removal tool more akin to a Swiss Army Knife. Yes it weeds out the likes of tracking cookies, browser hijackers, toolbar installers, key loggers and trojans as you'd expect, but it also features real-time "OnGuard" protection. This incorporates a pop-up blocker, cookie and browser monitor, ActiveX Immunizer, Site Guard (a list of known fake commerce sites) and a scheduler (great for automatic scans and live definition updates).

Tests on several PCs consistently had SD returning more results than Spybot - with quicker scan times. You receive some of the best descriptions we've seen: what is found, who it's from and what it likely does to your system (ideal in deciding whether or not to delete an apparently malicious object). Navigating your way around SD couldn't be more straightforward and everything always worked as expected - although we did notice a small window size/location bug on one particular test PC with dual displays.

If you're serious about protection then yes, Spyware Doctor's speed, ease of use and extra-features are worth the nominal outlay - although we'll still be keeping the free version of Ad-aware just to keep SD on its toes.