I recently purchased my first mountain bike about a month ago, and I'm looking for advice/commentary on my current status and future plans. I will add the current specs below.

Bike: 2002 Trek 4300
Fork: RST Marin 381rm
Shifters : older xt 3x9 pair
Brake levers: Avid Speed Dial 7s
Bar: Easton ec90 flat bar
Rear Der.: M772 xt shadow long cage
Front Der.: XT
Grips: Ergon GP1
Cassette: 9 spd XT
Cables/housings: Red jagwire kit
Saddle: New take-off from a specialized hard rock.
Everything else is stock.

Total spent so far, $330

I want this bike to last me for around 4 years. So is there anything else I need to change? Should I swap the fork out for a 1998 Marz. Z2 BAM! ? Have I done well on the build so far?