Technical,
Spy Sweeper v2.6.1 is another great software IF Ad-aware Pro and Spybot - Search & Destroy didn’t find anything.
I had Spy Sweeper for 3 months and didn’t find anything after I run Ad-aware Pro, there is no point having another software if Ad-aware Pro is doing it job finding as long as you keep it up to date all the time than you are okay.
I don’t see why not have another software just in case if Ad-aware Pro and Spybot - Search & Destroy are not up to date on the Patch file, have to many protection software can take up a lot of system menory.
If you believe your protection software is doing it job well then their is no point having another one.