Trek 4300 - "Upgrading"

[Mr MEE]

I'm a newbie to the whole MTB scene and want to know opinions and suggestions if it will be worth to upgrade a few components on the below entry level bike.

 

TREK 4300 - 2007 model ( had the bike about a year now )

 

Shimana Alivio Groupset

Rock Shock J1

 

1. From V Brakes H Disc brakes, but will probably need to get a new wheel and hub. Any suggestion as to what to buy or how much to pay?

 

2. Maybe a new groupset SLX or so.

 

Not looking to spend more than R2500 .....

 

Or will it be worth it save up 5 to 10k, pawn the bike ( don't know it's worth, can't be much though ) and look for something else 2nd hand.

 

Any suggestions?