h/d

hi friends, my present config is: proccy: intel p4 (2.66 GHz) mobo: pcchips P21G (V 1.0) RAM: 256mb ddr H/d: 40 Gb pata i'm not willing 2 spend much. so i'm plannin 2 buy 512 mb RAM ddr & a SATA 160 gb h/d. will my mobo support this or do i hav 2 upgrade whole of the thing...