That download is a trial version, that only works for 4 hours after each boot. You have to pay for the uncrippled version. The price is $39 USD, 26 euros, 20 GB pounds. I tried it with a decent speed 4 GB Sandisk pen drive, and uninstalled it after 2 days as I kept getting BSODs and strange freezes. Personally I found no increase in responsiveness on my 3 GHz Pentium 4 system with 1 GB of RAM.
The impression I got from reading web reviews is that this software will do little for a machine unless it has less than 1 GB of RAM and a slow hard drive, (like many laptops) and you definitely need a usb 2.0 high speed port.