What is ready to boost? - Windows Vista Ready Boost

While I rarely use my Windows Vista laptop at home, I happen to use it to convert my PowerPoint 2007 files to 2003 version and sometimes to copy slides from 2007 to 2003. As I was copying my slides from my USB thumb drive to the laptop, I noticed an unusual (for me, it is unusual) prompt aside from the typical do-you-want-to-open-this-in-Windows-Explorer type of question.
It gives users the option to use the USB thumb drive for ReadyBoost, a feature in Windows Vista which allows you to use a non-volatile flash memory, such as that on a USB flash drive, to improve performance without having to add additional physical memory. Now, this is cool especially when you don't have the "ca$h" to buy additional RAM or if your motherboard does not support additional physical RAM, like maybe limited to a maximum of 2GB. What I did notice is that there was some increase in performance using a 1GB USB thumb drive. The reason I didn't get to see this with my other USB thumb drives/SD cards is that it has to be at least 3.5MB/s before it can be used for ReadyBoost. But still, it's worth having a cheap USB thumb drive to be used as additional memory for your machine although performance is not as good as a real physical RAM