This the text from the "This vs. That" thread that is stickied at the top of the Beginner Brewing forum. (which is what tchuklobrau is referencing, I believe)
Plastic Water Bottles:
Pros:
* You can find them anywhere
* Cheap
* Less expensive than glass carboys
* Translucent, so you can watch the fermentation
* Firm seal with a cheap stopper, so you can be sure to get that happy music out of your airlock
* Light weight. Easier to move and cheaper to ship than glass carboys. Also easier to sanitize than glass carboys if you use the Llama method of 1 gallon of water, Star San, and shaking the **** out of it for a few minutes
* You can drill a hole and install a bulkhead to create a racking modification similar to that used with better bottles
* Some of them have built in handles
Cons:
* Some aren't made of #1 or #2 plastic, making them unsuitable for our purposes
* IMHO, they look cheaper than the buckets
* If you do get an infection (which is uncommon, borderline rare with proper sanitation) you'll most likely have to throw away any plastic equipment to prevent further batches from becoming infected.
* Translucent, which can allow light in. Easily remedied by draping a dark t-shirt over the bottle
* Made of plastic, which can become scratched if you try to use a carboy brush on them
* Cannot handle negative pressure. You might still be able to get away with a wort wizard if you burp it as with a BB
* Any plastic gear you use will eventually need to be replaced. Sorry, but it just won't last forever
* Does have higher oxygen permeability, so you might not want to bulk age in a water bottle for more than a few months
So, IMHO, the oxygen permeability isn't an issue with the short time that your beer will be fermenting. If you decide to age some wine or stronger beer styles it might pose an issue. The main issue for you would be deciding if the plastic type is correct and if it's not, does that bother you.