Read this with interest yesterday and last night installed it on my PC.
Recently I have been suffering a slowdown on the net, looked like there was a virus but all ran clean and when I went back to the PC after a few hours the memory had dropped from 170 Mb free to about 88Mb, requiring a reboot.
After installing this software the pages (seem to) load faster and after leaving the PC for a while the memory was all still available so this has got my vote