@ashnik and susk21 thanks for the reply.
i already have a PC P4 520 , 256 RAM , DVD combo drive, 17in monitor etc etc. I want to build that Media center so that it can replace my dumb
DVD player which doesnt play DivX etc and also want to record TV as i have a digital settop box . I have seen some digital video recorders with hard disc but they are expensive. so insted of investing money in that i want to build a Media Center for my living room in the near future. I want to wait for some time so that a high quality video output card is available and for some more powerful Processors can be affordable.