If your want to make your pen drive as a RAM, then Follow these steps :-
1. Insert the Pen Drive (1GB at least) in the USB port
try to prefer 4GB.
2. Let the PC do what it wants to do to detect it..
3. After it finished his work, you have to act smart,
4. Right Click on My Computer -> Properties
5. Advanced -> Performance Settings
6. Advanced -> Change
7. Select the Pen Drive
8. Click on Custom Size
9. Check the value of space available "
10. Enter the same in the Initial and the Max columns
" You just used the space of the PenDrive as a Virtual Memory "
Restart... Your PC is fast and furious