Mountain Biking - Upgrades for a Boulder SE?

I just got into biking with a Boulder SE that I picked up about a month ago. Since then, I've put about 400km on the bike, and I have to say: it's falling apart. Aside from getting a better bike, which I'll do in the winter, what could I upgrade on this bike to make it better? My main problems with this bike are:

1. The wheels need to be retrued all the time
2. The rim brakes suck
3. Shifting is sloppy

What kind of riding are you doing on that bike?

Your not using it at the local skate park or for 'urban assault' are you?

1. The wheels need to be retrued all the time
2. The rim brakes suck
3. Shifting is sloppy
1. Have the wheels completely retensioned, or think about buying a new set. What sort of riding are you doing? A good wheelset may be worth spending money on, since they can be easily transferred to another bike.
2. Adjust the cable tension properly - clickety click (http://www.parktool.com/repair_help/howfix_linearbrakes.shtml). Maybe look into upgrading the brake pads (Kool Stop pads are great).
3. Adjust the cable tension and derailleur. Rear derailleur (http://www.parktool.com/repair_help/FAQrindx.shtml). Front derailleur (http://www.parktool.com/repair_help/howfix_frontderailleur.shtml). Follow the instructions from start to finish to be sure everything is right.

I ride in parks, up and down grassy hills, with some ashphalt trails. Usually, I do around 20km/day.

I've got a Boulder SE with about 400 miles on it and it's fine so I'd have to chime in with Stubacca and say its in the set up. I've ridden mine on mostly XC type single track - Tsali, NC and such and the bike has really done well - actually better than I should reasonably expect now that I've gotten a little more educated since buying that bike.

Their not really up for park use and it may be the problem. Think XC and trail use for beginners.

I don't think he means parks as in skateparks... I think he is talking city parks.

I don't think he means parks as in skateparks... I think he is talking city parks.

Yes. Although 25% of my regular tour is off-trail. It seems as though this bit is the hardest on my bike. But, good news! My LBS let me trade in the Boulder SE, and I upgraded (major understatement) to an Iguana '05. I took the bike out tonight for a 40km ride, and while the disc was rubbing the calipers, this went away after about 30km of riding. Do new disc brakes initially have this problem, or should I get worried about something?

Pad rub on new discs is common. Once it is gone, it shouldn't return unless the brakes need adjusting, or perhaps if and when you change pads.

Cool! I like a happy ending!