On my regular travels around the web, I stumbled upon a brilliant resource for information around Windows Vista; Tom Archers's blog.

One of his more recent posts, from June 2nd, gave a Q&A on a new feature in Windows Vista, namely ReadyBoost.  Now, you may be thinking, what is ReadyBoost?  Essentially, ReadyBoost is a Windows Vista feature that allows you to use a USB key, or, a number of popular memory cards, as virtual memory in order to enhance performance.  It is important to mention, that currently, memory cards are only supported when used internal card readers.

Tom's post goes on to give an excellent FAQ, provided by Matt Ayres, all about ReadyBoost.  Some of the ones that I found particularly interesting include:

Q: What's the smallest ReadyBoost cache that I can use
A: The smallest cache is 256MB (well, 250 after formatting). Post beta2, we may drop it another 10 MB or so.

Q: Isn't this just putting the paging file onto a flash disk?
A: Not really - the file is still backed on disk. This is a cache - if the data is not found in the ReadyBoost cache, we fall back to the HDD.

Q: What happens when you remove the drive?
A: When a surprise remove event occurs and we can't find the drive, we fall back to disk. Again, all pages on the device are backed by a page on disk. No exceptions. This isn't a separate page file store, but rather a cache to speed up access to frequently used data.

Q: How much of a speed increase are we talking about?
A: Well, that depends. On average, a RANDOM 4K read from flash is about 10x faster than from HDD. Now, how does that translate to end-user perf? Under memory pressure and heavy disk activity, the system is much more responsive; on a 4GB machine with few applications running, the ReadyBoost effect is much less noticable.

There is also an excellent resource over at the Microsoft website, on the Windows Vista Performance Enhancements page.  It gives a great description of how to actually configure and use ReadyBoost.

Unfortunatly, I've only got a tiny USB stick (careful!) weighing in at 128Mb, so not quite up to the minimum size at present, so I haven't used this myself, but for anyone running Vista, who may have less RAM than is optimum, buying a cheap SD card or USB stick may be a great way to really 'ReadyBoost' your system :-)