buy a Media player ..because it can play any file u throw on it!!! even u can copy a blue-ray disk and watch it on ur media player!!!!
for a media player u have 2 options.....one with hard drive and and one without(if u already have a portable Harddisk).
I use a Media player Boxee from Dlink..its awesome!!! but if budget is a concern..buy the Asus O mini(its for 4200Rs.) its small in size but plays anything u want!!!! But both boxee and asus omini will need an external hard disk to play ur movies from!!!
But if ur planning to buy one with a Hard drive it will be bit expensive!!!!