I think that if you have the money it's a worthwhile upgrade The main difference that you'll feel is the fork, a new one will be much lighter than the onza original and so make backwheel maneuvers easier. the fork i suggest is the echo lite '07 - it's great value. For you front wheel I think that either the hope XC or Pro 2 will do depending on your budget. Both come with disk mounts and look bling . A nice rim is the echo '07. Finally, the disk brake I would go for if i was you is the avid ball bearing 7. Not only is it half the price of some other brakes, it also outperforms many of them! At the end of the day it's up to personal preference, but these components are good choices and will make quite a difference to how your bike looks and performs. EDIT Oh, i didn't realise you still had the original bars and stem. If i were you i would put the disk brake upgrade on hold and look at bars and stem. They will make a bigger difference for alot less money