In most cases, the USB Stick or SD card are not even fast enough to make Readyboost worthwhile.
I know when Vista launched, there were flash drives that were certified as Readyboost capable, meaning that they had the speed of the device had to meet certain requirements. Now, you can connect any old USB device to the system and it will ask you if you want to use Readyboost even if it's just another rotating disk.
If you want to reap the benefits of flash memory, you need to plunk down some cash for a SSD. In your case, Lenovo has an accessory for your notebook that would let you install a 2.5" drive into your optical bay. Get as big of an SSD as you can afford (80-120GB deepening on your needs, more if you are Mr. Moneybags) and drop it in.
You can clone your install over or do a fresh install. After that, set the system to keep your docs, pics, movies, etc on your Hard drive so that the SSD has room for Windows and Apps - the things that are important to have on an SSD.
Lenovo SATA bay adapter