HOWEVER...just for the "nobody should ever ride a wall-mart bike ever" crowd...Here's my story:

I have, for the last 18 months, been riding a $200 wal-mart Scwinn Varsity 1200 flat bar bike (hybrid, or flat-bar road bike, you choose the name.) I got the one with shimano trigger shifters, solid modern threadless stem, and tourney components (twist shifters are the devil...always...always...in fact this same bike now has twist shifters and a few other downgraded components, I would not buy it now). And it works for me because I am an on the small side of being an average sized man (5,9" 160 lbs)...these bikes have no size options.

Soon after purchasing, I took it to a local bike shop and had them tune it up for $45, replace the rear cassette which was already loose, and do a safety check. It shifted and operated MUCH better after that...they said the front derrailer was clamped on to the seat tube at the wrong height).

I've since ridden it about 50 miles a week for 18 months. 30 commuting, and a 20 mile "B" level local bike group, which has a 16mph average (some big hills, so they actually cruise around 20mph for a lot of the flats.) They are nice and don't make fun of me, at least to my face...probably because they know how hard I'm working to stay with them on a bike that weights 10 lbs more than theirs...

Other than occasional adjustments of the deraillers & brakes, replacing brake pads, replacing the chain (all done myself), I have had ZERO problems with it. It weights 28 lbs, and has 28mm tires, and for along time I was tweaking the seat position to get comfortable, but I've got it pretty much dialed in now. It has recently developed a bottom bracket squeak that I haven't been able to fix yet, but it operates flawlessly and shifts easily and predictably...unless I'm trying to shift down the front ring while climbing a steep hill.

After about 5 months of saving and research and riding at bike shops, I have just ordered a Jamis Quest Comp (MSRP $979) which I hope to pick up next weekend. It will, admittedly, be a huge step up for me, and will likely give me an immediate mph or 2 for similar effort...but the walmart bike has served me well, and allowed me to really see if I would stick with this bicycling thing.