Clydesdales/Athenas (200+ lb / 91+ kg) - Hello all. Should I stick with this bike or try and get a new one?

My parents recently got a new bikehttp://i176.photobucket.com/albums/w183/eriksoto/IMG_20110523_201843.jpg and It's been pretty good to me considering I'm 6'2 and 230 lbs. I had a blast since it was windy and I haven't ridden a bike in forever. I only got to ride it for about 2 and a half miles since it started raining. The only problem I have with it is that the back wheel goes down when I sit on it and the squeaky seat.

The bike from what I got from the body is a "Sea Pines Huffy 3 gear" and my parents got it from an old couple who didn't use it anymore. I was wondering if I should keep it and fix the wheels if they break, or, since my High school graduation is this week if I should ask for a bike as a 'graduation present' since it's pretty hard to get them to spend over $600 without a special occasion. I also don't want to buy a cheap one from Target/Walmart and have it break on mea day or two later. I've been browsing the forums for a bit and have seen bikes go over $1000. I Just want one that i can use on the road/sidewalk and the rare dirt road.

I can't imagine a high school kid willing to even be seen on that bike! with that said, if it works and is rideable, it may be worth riding but i'm with you, asking for one may not be too bad of an idea. i would start searching craigslist. look for something in roughly a 60cm frame or even a 62 or 63cm frame for it to fit you. Those $1000 road bikes are often being sold used for a fraction of that after sitting in someones garage. You can also look into a site like bikesdirect.com but you will need to assemble yourself or pay a bike shop to do it but even then you can get a really nice bike for about $500 and pay $50-$100 for assembly at a bike shop.