The above link is broken but from that i can got freenas.org which is a Software based solution. This doesn't solve the problem see if u want to have a Torrent Downloader it will require a Little more power. And P2 or P3 are not compact. They will not Support Sata don't tell abt PCI sata card it will really increase the budget.
Now can anyone suggest other solution ? Do we have a enclosure or some thing like that for this ?