That's a tough question to answer. You first need to decide on your goals. Surge is not a "instant" result product. Rather it's a product to help facilitate muscle growth via taking you out of a catabolic (muscle-wasting) environment to an anabolic (muscle building).
To be politically correct catabolic means broken down into something simpler while anabolic means being created into something more complex but for the sake of simplicity we'll only apply it to muscle building.
I have never tried Power Drive. I haven't really seen enough supporting evidence for the product outside of Biotest to warrant me giving it the green-light. The reports I've read of users who have tried it though claim that it helps you get in the "zone" per sae and helps prime the nervous system. If this is the case and the stuff does work as claimed (and being that is Biotest this is highly probable) then you should see instant strength increases of a few percentage points. Oh wow a fer percentage points you say. Big deal. Uhhh no.
For example I was ecstatic the other that I benched 355 was previous record was 345. That's about a 3% improvement and took almost 6 months to facilitate.
I'll get around to the "easier to read" version of why Surge works in a bit.
EDIT - I feel I need to correct my post. In saying I haven't seen enough evidence about Power Drive is not saying that I believe the products to be non-effective. Rather it's just not a product I was interested in so I never really looked into it besides the info on T-Nation.