Front and rear drive help KONA UHU

[skki]

Guy's need some help please ive got a 97 Kona Uhu which needs new new ring/cogs front and rear ive got Shimano Deore LX, so where can i get new rings and rear cassette?? is there any others i can use? Im told i can use a HG rear cassette instead of an IG is this correct.
BTW im using an IG51 chain

I know neebie stuff but im into restoring BMX's but ive had this UHU for years and it still rides great apart from chain slip now