As the saying goes, "If it ain't broke, don't fix it." Over the course of the past few years, Spyware Doctor has been at the top of its game. The program's one of a handful of anti-spyware tools that has managed to not only keep up with these threats, but also beat back even the toughest of challengers.

Given its success it would be folly for PC Tools to tinker with its flagship product too much, yet the company's managed to produce worthwhile improvements with the release of Spyware Doctor 5.1.

This time, it's all about performance and simplification. Spyware Doctor 5.1 is a leaner and meaner version of its former self. The program now starts faster when Windows is booted up.

It also consumes less memory when running in the background and scans can be set to run at a lower priority so as not to interfere as much with other tasks. Simplification comes in the form of improved scanning screens that keep you well informed about your PC's security status.

Simple, but effective

As expected, Spyware Doctor did a great job of detecting the threats present on our test system, clearly ranking them by threat level and removing them with ease. Integration with XP's System Restore feature makes it easy to create a restore point before removing threats, enabling you to move back in time should removal lead to problems.

Definitions and updates are downloaded and installed automatically, and scheduled scans ensure that prevention and detection are taken care of with virtually no user intervention required.

Of course, every program has its quirks and Spyware Doctor is no exception. Its "OnGuard" real-time protection tools aren't enabled automatically, but turning them on is only a single-click away. Scanning for hidden rootkit files is also disabled by default, but again this is easily enabled from the program's Settings screens.

At £30 for a single PC license the program isn't exactly cheap, but it's still a great investment. You'll have a hard time finding a better anti-spyware program.