Will the Windows 7 benefit from a ReadyBoost usb flash disk (or sdhc card) even if the system drive (partition where windows is stored) is encrypted with TrueCrypt 7.0a?
Sure it will, TrueCrypt is transparent...
If the kernel writes something to the disk it will get encrypted,
if it reads something from the disk it will be decrypted.
Nothing bypasses this so you don't have to worry about something reading the pure encrypted data.
Unless you hang the drive to another system ofc...
This is an extract from another forum http://www.windows7news.com/2009/11/17/windows-7-readyboost-what-is-it-how-to-use-it-and-does-it-work/. I thought it might come handy
1) Readyboost will never report the cache as RAM. If you have 1 GB, that is what it will report. It is not a RAM extender but simply a cache for repetitive read/writes to make hard drive activity more efficient.
2) The smaller cards you are using are too small, and SD cards (of any size) are a bit slow with respect to read/writes at the best of times.
3) Readyboost does not have an immediate impact on performance. It is one of several bits of adaptive coding in Windows 7 and it doesn't intially know what apps, etc. you run. As a general rule, I have found it takes at least a few hours of use before it has any effect.
4) If your machine is constantly hitting 90+ percent RAM usage, you have a different problem. That is excessive by any estimation. Leaving that aside, Readyboost will not make that RAM usage drop by 1 percent anyway. It is caching repetitive read/writes to improve drive performance, not limit RAM usage.
5) If you are looking to improve performance, check to make sure your swapfile is setup correctly, take a look at the task manager to see what is tying up all of the system RAM, run msconfig and remove unnecessary startup apps, and/or add RAM to the system.
First, note that the contents of your ReadyBoost cache are encrypted and compressed, but I'm not sure how strong this is - you can assume it can only be decrypted by the local machine, but how easy that is to break I don't know. Since you encrypt your system drive I mention this as it may be of interest to you.
Secondly, how much ReadyBoost helps your system is most dependant on how much RAM you have (the more RAM you have, the less you'll notice the effect).
If you have a spare drive or card, I'd stick it in and give it a try - you don't have to destroy the contents of it either, as ReadyBoost can just use any spare space on the drive/card.