Nitrogen, all of the testosterone replacement therapy clinincs that I have seen that are prescribing testosterone for patients are using steroids. I have never heard of any form of testosterone that is not schedule III; if you've got a link, I'd love to read more about it. Here are a couple of ads from the internet:
http://www.real-testosterone.net/?source=overture_testosterone
http://antiaginggroup.com/?OVRAW=TESTOSTERONE&OVKEY=testosterone&OVMTC=standard
All of these forms of testosterone (test cyp, test prop, test susp, deca) are schedule III controlled substances. They are legal for doctors to prescribe for hormone replacement therapy, but unless you've got a testosterone deficiency or hitting midlife, it's unlikely that you're going to find a doctor to prescribe steroids to you.
Note how the first ad uses Clomiphene; this is to combat the increased production of estrogen due to the testosterone therapy (gynocomastia, or b!tch tits, is one side effect of steroid usage). Another side effect of using testosterone is that when someone is using steroids, their Leydig cells shut down, effectively ending natural testosterone production. There are drugs to 'kick start' the Leydig cells after steroid usage, but there's no guarantee. Also, if one remains on steroids for an extended period of time, the body could permanently stop producing testosterone naturally.
The new generation of over the counter products can also have similar severe negative consequences on one's body.
And as benign as many think that creatine is, there are a couple of studies that show prolonged use can effect the electrical impulses in the heart. A cardiologist (and weightlifter) friend of mine recommended cycling creatine for no longer than two months on, one month off due to the effect that creatine can have on your heart.
At this point in my life, I've personally gone completely 'natural,' with only vitamins and protein supplements. (Too many long term unknowns about the current over the counter supplements). Personally, I think that as long as you feed your body an adequate supply of protein, have a healthy diet, and get enough rest (sleep), you are going to achieve very close to the results that you would with steroids or all of the gimmick supplements out there.