some facts & fiction : vista includes a new feature called readyboost.(
actually ReadyBoost for hard drives already exists 
it's called "page files" 
) pls note that this doz not put the paging file onto a flash disk; the file is still backed on disk; this is a cache. if the data is not found in the ReadyBoost cache, it falls back to the HDD. with this feature, u can speed up ur pc, with a usb memory !
vista supports the following form factors for ReadyBoost:
-USB 2.0 fl ash disks
-Secure Digital (SD) cards
-CompactFlash cards
normally windows uses a portion of ur hard disk as a sort of a scratch pad, writing temp data 2 it while it works. but hard drives r much slower than memory. so the readyboost feature lets u use a usb drive (or any of the 3 above) instead. as soon as u plug it in, u get a popup screen asking u to open the files or to 'speed up the system'. clicking on the latter lets ur usb drive act as a 'scratch-pad'.
ReadyBoost takes advantage of the fact that flash memory offers lower seek times than hard disks. essentially that means that your system can get to a given location on a flash disk more quickly than it can to a corresponding spot on a hard disk. Hard disks are faster for large sequential reads; flash disks are quicker for small, random reads.
ReadyBoost does not support external card readers ! nor is there support for multiple ReadyBoost drives presently !
(however, Microsoft has indicated that multiple-drive support is under consideration for future versions )
but which usb drive ? anyone just wont do ! it has to be compatible.
the baseline requirements r :
The USB Key must be at least USB 2.0
The device must be able to do 3.5 MB/s for 4 KB random reads uniformly across the entire device and 2.5 MB/s for 512 KB random writes uniformly across the device.
The USB Key has to have at least 230mb of free space
Grant Gibson has compiled a pretty exhaustive list of some readyboost compatible drives...
how much of a boost can u xpct from ReadyBoost ? as with so many other performance issues, it depends. if ur internal memory is well above the amount you actually need, ReadyBoost won’t do much for you.if not, xpct to c some REAL improvement !
there r sevrl ways being sgstd on the net as to how to make ur usb compatible with some hacks/tweaks. here is one for eg :
1. Plug in the device.
2. Access your device properties: Start Pearl > My Computer > Right click device > Properties > Readyboost Tab
3. Select, “Stop retesting this device when I plug it in.”
4. Unplug the device.
5. Open the registry editor: Start Pearl > Type regedit in the search bar
6. Access: HKEY_LOCAL_MACHINE / SOFTWARE / Microsoft / Windows-NT / CurrentVersion / EMDgmt
7. Make the following registry changes:
- Change the Device Status to 2.
- Change ReadSpeedKBs to 1000.
- Change WriteSpeedKBs to 1000.
8. Plug in the device and Readyboost should work
source
but using such methods only fool
vista into thinking that such usb drive r compatible.
but no performance gain is noticed ! u also risk losing data if you remove the device before shutting it down in Vista.
in reality, you are not speeding up the operating system, since the computer is using the computer's hard drive and not the USB memory for the Readyboost. expect little or no performance gain when using this on incompatible devices !!!
The Vista ReadyBoost Feature.
Linear Mode
