Did you know that:
 
In Windows Vista, you can use your USB flash memory (thumb drive) as additional virtual memory for your computer?
 
Find out more: http://www.microsoft.com/whdc/system/sysperf/accelerator.mspx
The use of a flash device that supports Windows ReadyBoost technology extends the disk caching capabilities of Windows Vista main memory. ReadyBoost-capable devices can be implemented in a variety of form factors, including USB 2.0 flash drives, Secure Digital (SD) cards, and CompactFlash cards.

Using ReadyBoost-capable flash memory devices for caching allows Windows Vista to service random disk reads with performance that is typically 8-10 times faster than random reads from traditional hard drives. This caching is applied to all disk content, not just the page file or system DLLs.

Of course, most flash devices are slower than the hard drive for sequential I/O. To maximize performance, ReadyBoost includes logic to recognize large, sequential read requests and then allows these requests to be serviced by the hard drive.

An external ReadyBoost-capable device could be removed at any time. As a result, one of the design goals for ReadyBoost was to ensure there could be no interruption of system service or loss of data when removal occurs. All data writes are made to the hard disk before being copied to the flash device, so every bit of data held within the flash device is safely duplicated on the hard disk.

After some period of usage, the flash device will likely contain sensitive information. ReadyBoost encrypts the content for use only on the PC system where the data was generated.