More memory to your Windows 7 system

Just learnt about ReadyBoost… been there since Vista!? Learn more about ReadyBoost in Windows 7.
Note, does not work if you have an SSD drive already. Similarly won’t work if your SD card is quite old and not fast enough to make a difference. Also depends on the type of file system… exFAT seems to be the best (whcih seems to be limited to 4Gb).