If u have low Ram On vista u don’t have to upgrade your ram.U can Use Your pen drive as a ram.
In order to activate the ReadyBoost technology on your FlashDrive or Memory Cards, you have to follow these steps…
1. Open My Computer.
2. Right Click on the Removable Disk Drive and select Properties.
3. Click on ReadyBoost Tab.
4. Enable the feature by selecting the option and allocate the amount of space you want to use as memory.
Things to be noted….
1. Regardless of the fact that you use Readyboost or not, you need at least 512 Mb of memory to run Windows Vista decently.
2. If your device is not giving the option of ReadyBoost then it means that it doesn’t clear up the minimum data trasfer rate required by ReadBoost technology.
Here is a video tutorial for Windows Vista Readyboost: