Q: i find my pen drive not fitting into the socket in cpu??? can one use any pen drive in windows xp or there are any restrictions?? now how could i fit my pen drive into the cpu?
A: Assuming you mean "computer" and not "CPU" (since a CPU is a small chip: http://www.fileshosts.com/pentium4/ES_sample/1/cpu_00.html ), it is just a matter of plugging it into a USB socket (which are entirely standard, and its been all but impossible to buy a machine without USB support for the past decade). If it doesn't fit, then it is probably physically damaged (or you are trying to insert it in upside down).