I am a pharmacist. Paxil and the other SSRIs have proven very beneficial to many, many people. There will always be people who believe you should not take psychiatric medications of any sort, but truly, when you have a chemical imbalance, they can work when nothing else does.
Valium is far more addictive, both physically and psychologically. It is a controlled substance for that reason. It's not as bad as most of the narcotics (Vicodin, Percocet), but it still can be a problem. Paxil is not controlled, and there is no evidence of addiction. That being said, it is recommended that you taper off gradually if you decide to stop to minimize withdrawal symptoms. This is because of the chemical imbalance I mentioned earlier. Your body does get used to Paxil in the sense that it changes serotonin levels, and when you stop, those levels will change again. Another thing of note: it takes several weeks to truly feel the effects of all the medications in this class. Some people may notice an improvement sooner, but you shouldn't give up on it until you've been taking it 3 to 4 weeks.
Your "what if" thinking should improve, so hopefully you won't be worrying about what will happen. I can tell you this: even if the computers crash, most pharmacists would never leave you without any medication unless there is a very good reason. If you have an established pharmacy, go there regularly, and have a bottle, even with the computers being down, they would most likely give you at least a few pills to get you through in a worst case scenario. Think of all the hurricanes we had here, particularly in 2004. I was working at a hospital in Pensacola when Ivan hit, and we were making sure that people in the shelter who forgot their maintenance medications were getting a supply of at least a few days (with an MD"s OK, of course). Pharmacies have back up plans for power failures (particularly in Florida!).
Ultimately, you have to decide what is the right course of action for you, If you are uncomfortable with taking a prescription at this time, talk to your doctor about other alternatives. If you are concerned about a particular drug, ask questions. Feel free to email me with more questions.
BTW: weight gain dose happen, but it is an infrequent side effect. Paxil and the SSRIs more commonly cause weight loss.
Wellbutrin and Lexapro were recommended by some of the others, but you should know that they are not currently indicated for use with OCD. That doesn't mean that they still couldn't help you, but since you specifically talked about the OCD symptoms, you would probably want to try a med that does have that indication.
Hope this helps.