if your bikeshop gives you that look. its most likely that they are trying to make you buy a bike from them. if I were you I would go to a different bike shop, if possible. A respectable and honest bikeshop would not look down upon an any bike...cause thats against the spirit of biking......remember the best bike for you is the one that fits you: your body, your pocket, and your riding needs. If someone is happy with a X-mart bike...so be it....its all about having fun......isnt it. so you should ask yourself that are you having fun.....and that should not include peer pressure.....being yourself is the coolest thing you can do....just by being like "others" you will become one of many....

GT Avalanche 3.0 is a nice bike for entry level riding. Mountain Bike magazine gave a good review of its bigger brother Avalanche 1.0 (1.0 and 3.0 uses the same frame but different component groups, so they are at different price point). So, if you swap a few parts around you should have a pretty good bike for XC and trail riding.

now if you decide to change the front and rear derailleurs here are some really cheap deals:

Front:

http://www.jensonusa.com/store/produ...r+M510+Oe.aspx

Rear:

http://www.jensonusa.com/store/produ...illeur+Oe.aspx

Crankset:
http://www.jensonusa.com/store/produ...ankset+Oe.aspx

Cassette:

http://www.jensonusa.com/store/produ...tte+05+Oe.aspx

there are some other great prices in this website too. Also check the www.pricepoint.com, they have some good prices on components. Finally, before you buy anything please check that whether your wheels will be able to fit the cassette and RD (8/9 speeds)....

Upgrading components on a bike that already fits you is great. specially if the upgrade is gradual, it does not cost you a lot at one time. I think, if you upgrade to the full deore set up, you would have a great and smooth shifting system.

good luck.