OK...here is the real deal.
Windows 7 is king over readyboost, in that it allows you to use multiple devices to boost its speed, and allows up to 256GB of memory.
As far as what you need to do it? Not all memory sticks work, and the actual requirements for ready boost are all on hard to find specs. Most flash memory sticks will advertise their read/write times, yet ready boost doesn't really care about that. Instead, it is looking for a lightning quick access time of < 1ms, and requires 2.5 MB/second READ speeds (for 4KB), and 1.75 MB/second WRITE speeds (for 512KB)... and these last two have to be consistent throughout the device.
These spec's are hard to find.... not that it is hard to find a device that meets these, but rather that these specific spec's are simply not published most of the time.
This is like trying to buy a car based on the thickness of the windshield... even calling the dealer they will probably not have any idea.
Most flash sticks will give you read/write speeds, but these are averages. This means that one part of the stick might be higher, and another lower... many 'high speed' sticks actually have one segment of lightning fast memory, and the rest is slow. Another problem, here, is these are sustained speeds... readyboost requires much smaller read/write access... which means that a device that responds in 1.2 ms, and then reads at 300 MB/s simply will not work... no matter how fast its listed read speed is.
Again, most manufacturers don't broadcast these spec's because for most uses, they are trivial. Most of the time, the read/write speeds you see are for large files, where access time shows a diminishing return very quickly.
Really, the best indicator of how well a flash stick will perform is access time. If the read/write speeds are high enough, and you find a very fast access time, you have a winner.
Here is a list of access times:
http://www.tomshardware.com/charts/comp ... e,846.html
Much of the confusion as to how well readyboost works seems to be because there hasn't been any credible source doing any reliable benchmarks using well spec'd flash cards. Rather, you have a guy on the net that says "I tried it, and it didn't do much..." Somehow, I don't find that credible. To be a convincing benchmark of readyboost, you would need to isolate three factors... the system(s) that you were using (and you will need high, med, and low spec'd systems to compare), the flash memory that you are using (and again, you will need to be forthcoming about the actual spec's that readyboost relies on), and the types of applications that you are using for the benchmarks.
As for other memory devices? SD, etc? I wouldn't even bother. Most of these devices are internally wired up to a USB port, and therefore will show diminished access times vs a USB port by itself. In addition, access times are even harder to find on SD card than they are on Flash sticks... for the exact same reasons.
As for how much of a boost will you get? That depends on your system. Memory generally trumps readyboost, and readyboost will see diminishing returns as RAM increases. In general, the best scenario for it is a system with little memory, or at its memory cap... such as an older laptop. Once you get into the realm of 4GB, there is really no advantage to ready boost at all, and it can, in fact, slow down your system. This isn't me pissing on your parade, this is Microsoft's word on it.
A lot of people want to boost their already high end system, but it simply won't work that way. "I have 8 gig of RAM, so if I use a 32 GB flash stick, how great will that be?"... ummm.. like an equal spec'd 6GB system.
Think about it this way... if you hurt your leg, and it is in a cast.. which is faster? With or without crutches? Great, crutches for the win. Now you are an Olympic runner, in great shape... do crutches make you faster? Or slow you down? Right again...
Ideally, for those that wish to boost their systems to astronomical levels, and are wanting to try ready boost... I would recommend paying strict attention to the access times on the flash USB sticks that you use, and I would use as many of them as possible to avoid bottlenecks when the system is trying to access multiple files at once.... especially with a multi-core machine. I would love to see that benchmark.
thats what im doing. my main pc is my laptop, the sd card is int he slot in the front, cant even see it
You will probably need to manually enable TRIM and possibly AHCI. There are certain Windows 7 commands which will tell you if TRIM is enabled.