I really regret to hear this...
As most of you know by now, I ride a lot myself and even used to work as a mechanic in a bikeshop. I truly think that the biggest disappointment is caused by the low quality bike you decided to invest in. Quality parts really do make a difference, I don't know any other sector where the 'you get what you pay for' expression is more true than with bikes & their parts.
Give it a rest for a while, forget about your crap bike, put a little money aside once in a while when you can, and somewhere in the future, buy a decent bike at a good bikeshop where they can give you advice to find the bike best suited to your wishes/needs (and keep in mind that a well maintained 2nd hand higher end bike will most likely give you a lot more bang for the buck). Learn to do the basic maintenance yourself and you'll have a great, low cost hobby/mode of transportation...
If you need any advice, feel free to ask me.