I sold my Dell Dimension 8400, P4 3.2 HT, 1 GB RAM, DVD writer DL, CD ROM, 160 GB SATA, Gforce 6800, 256MB for Rs 25000/- in Oct 2007 after 19 months of usage. Had original packing, manuals and software.
You should be able to sell it for Rs15000/- easily.