Mountain Biking - How to know when to upgrade and what?

Hello,
This is my first post in this forum but I've been reading and enjoying everyone's thoughts for a few months. I've been riding since 2001 with my trusty Trek 4300 but two months ago made the plunge to FS and now have a spanking new Giant Anthem 3. Here are my present specs:
frame ALUXX Butted aluminum, 3.5" Travel.
fork Manitou R7 Comp w/ Lockout, 80mm travel
shock Manitou S-Type w/lockout
handlebar Easton EA30 Flat
stem Easton EA30
seatpost Easton EA30 350x30.9
saddle WTB Shadow V Team
pedals Shimano clipless
shifters Shimano Deore
front derailleur Shimano Deore
rear derailleur Shimano Deore
brakes Hayes SOLE XC
levers Hayes
cassette SRAM PG950 11-34
chain Shimano HG 53
cranks RaceFace Ride XC
BB RaceFace SRX ISIS
rims Mavic XM 317
hubs Formula Disc
spokes Stainless Steel
tires Hutchinson Python AirLight, wire 26x2.0

I read a lot about riders upgrading. It seems there are a couple schools of thought from what I can tell. One is to ride until something breaks, wears out or becomes a pain in the neck. The other is to identify the weak links in your specs and start there based upon your riding style.

I'd like some thoughts on where everyone falls on this and why. I purchased the Anthem 3 with the intention to upgrade as I know some of my equipment is bottom rung. Those of you who don't wait for things to break, what do you think is the place to start? I ride 4-5 times a week mostly single track with some fireroad and little if any pavement. No big drops but some jumps and the better I get the more climbs and technical riding. The only complaint I have thus far is that if my Deore gets any dirt or mud in it, it won't shift or shifts by itself. Is this a Deore thing and something I can rectify with say XTR or something I have to live with? I had the same problem with the Acera in my 4300.

Where are my weakest links in your opinion? Brakes? Tires/wheelsets? Drivetrain? Thanks for any thoughts and feedback.

First off, welcome to BikeForums!

Next, the problem you are talking about is not a Deore thing. If adjusted properly Deore will shift just pretty much as well as anything else. I really don't think you will notice enough of a difference to justify XTR. If you do want to change and you aren't loaded I wouldn't recomend going above XT.

If you really want to upgrade I always recomend going wheels and tires first. That is where I always notice the biggest difference. On top of that you can keep your old wheelset and put a different type of tires. This way you have one set ready for fast, flowing singletrack and one set ready for rocky, rooty trails. Or whatever combinations work best for your area.

The drivetrain I wouldn't upgrade until you start breaking stuff. Generally when you upgrade a rear derailleur or something without needing to that is when you will break a derailleur. Generally a couple days after buying the new one.

Other than that just upgrade what you want to, preferably with a goal in mind. Do you want lighter? Do you want more durable? Do you want to empty your wallet?

I just wait till it brakes or I have the money to upgrade something that I would like to. All the parts on my bike that I bought used are pretty worn down, so I right now I am just upgrading everything little by little untill I get a job and can afford a whole brand new bike.

How do you know when to upgrade? When something on your bike just isn't cutting it in what you want to do.

The way I see it, if it works for what you're doing then there isn't a reason to upgrade. If you want to, by all means go ahead but first consider if it's on par with what you want.

For example, I want a new frame because this one is a FS that I got where I lived previously. It just doesn't work for the more urban riding I'm in to where I live now.