ive got a dvd 2.1 srround thing, ive only got the2 speakers because of lack of room, i need a new dvd player and was wondering wether i need to buy a 2.1dvd player or can i use my existing sub and 2 speakers on a 5.1 dvd player

Please just upgrade to a 5.1 home cinema kit, there are plenty of kits that have really small speakers that will not take up any room at all.