Hello Tom,
I am also relatively new to backpacking, and have similar trepidation with a poncho tarp. My fear, though, is not with the poncho; it's with tarping in general. I'm always worried that in a high wind my tarp will fly away leaving me exposed to the downpour. I've had too many stakes blow out to completely trust them (and I've tried the lightweight ones sold here, Y-shaped ones, and thick rod-types). Placing rocks over them hasn't always helped, either.
Since beginning backpacking I've purchased and used Shire's Tarp-tent, GoLite's Hex 3, and the Gatewood Cape. The only one I feel will really hold up to a storm is the Hex 3, but you still need bug and ground protection, adding weight to an already (relatively) heavy tent. I know many people on this sight will disagree with me here, that the Tarp-tent and Gatewood Cape have weathered many storms successfully, but I still can't get past the feeling that I'm trusting my life to this thin piece of fabric with pullouts about to rip out. Also, try as I might, I still spent 10 minutes setting each of these up. Again, this is my inexperience talking. But I also like to camp high, above treeline on Mt. Hood in Oregon, where the winds can really whip up and storms blow in fast. So these are real concerns I have.
Here's the compromise I've come up with that gives me a real sense of security: I'm going heavier on the bivy (waterproof-breathable) and much lighter on the tarp. I've just ordered an Integral Designs eVENT Crysallis Bivy, shown here with BPL editor Mike Martin in it::
It's 25oz, but it has no skyward facing zippers and has bug netting down to its waist. It's brand new, so it hasn't been reviewed here yet, but the other ID eVENT bivys have received great reviews on this site for their construction and breathability. It may be that in GA it is too humid for a wp/b bivy. However, forum member PJ has experience with wp/b bivys on the East Coast, and has several posts about the ID eVENT Unishelter that are worth a read.
I will add to this a tarp I am currently sewing: it is 4 1/2 ft x 6 ft, weights 3oz, and is made from 0.9oz/yd Spinnaker cloth from http://www.thru-hiker.com. It's about as easy a sewing project as you can find (just sew a hem along the perimeter and add four corner tieouts), and it should set up faster than any other tarp I've tried. I will set this up in a diamond pattern like in this photo (but with a much smaller tarp):

This will provide plenty of protection for my gear and myself up to my waist. I will let the waterproof bivy take care of my lower body. On warm, muggy nights I can deploy the tarp and leave the bivy open to the waist (with the bug netting zipped in place). On a stormy or cold night, I can zip up partially or most of the way. Since the bivy zips up behind the head (rather than facing my feet), any opening I leave in the bivy will be pointing towards the tarp, not the open side.
On nights I'm not expecting rain I can just throw the bivy down and crawl in, knowing that if it rains I just have to zip up. I can enjoy great sunrises and sunsets that way. Or for a bug-free afternoon nap, I just crawl in and zip the eVENT down to the waist. And best of all, if my tarp blows away, I just zip up completely and wait out the storm in the safety of a fully-waterproof bivy.
Some might argue this isn't completely safe, as condensation might eventually lead to loft degradation. I will have to test out the eVENT breathability hype. This is one reason I will use the tarp, so that in most conditions I can leave the head area unzipped. I will also bring the tarp for entering and exiting the bivy, storing gear, and for making a lean-to during a rainy lunch break. But I can always fully zip up when it really comes down, which really gives me a feeling of comfort.
Gear comparisons (some biases here on what I think constitutes as necessary. I live the the Pacific Northwest, where I plan for all-day rains):
GATEWOOD CAPE:
Gatewood Cape, seam-sealed: 12 oz
TiGoat Bivy (L) w/ net hood: 7.5-9.5 oz depending on model
8 stakes (w/ side tieouts): 2 oz
Shock cord to hold bug netting away from face: 0.25 oz
Rab Pertex Quantum Wind Shirt (XL): 3.2oz
Large garbage bag (as rain jacket while you pitch the cape): 2oz
Silnylon arm chaps (optional, to protect your exposed arms using the cape in the rain): 0-2oz
Drop Stoppers Rain Pants (L): 4.5 oz
Gossamer Gear Pack Liner (slepping bag stuffsack): 1.5 oz
TOTAL: 32.95-36.95 oz
CHRYSALLIS BIVY:
Homemade tarp: 3.1 oz
4 stakes: 1 oz
Chrysallis Bivy (doubles as sleeping bag stuffsack): 24.9 oz
Drop Stoppers Rain Jacket & Pants (L, windshirt not needed–see BPL editor Carol Crooker's review): 11.1 oz
TOTAL: 40.1
So the waterproof bivy is 3.15-7.15oz heavier depending on your options, but provides a full rain suit and a fully waterproof, highly breathable bivy. Plus the bivy is a much simpler, faster system. I don't want to discourage you from purchasing the cape, as I do like the shelter and have personally met the maker. Also, many people here prefer ponchos for increased breathability. But if money is tight, and you are worried about storm-worthiness, you could put that money towards the eVENT bivy, the $15 highly breathable rain suit (almost as good as eVENT), and make a tarp for $30.00.
I hope this isn't too much info. It's just that is is very recent on my mind, and I have been in your place so recently in the past. Mind you, this is an untested setup on my part. But I wanted you and others to see that, when comparing all the related gear side by side, a fully waterproof, hightly breathable bivy with large bug netting really isn't that much more weight these days. This was a very recent revelation of mine, as I used to only compare shelter weight to bivy weight. You may prefer a more breathable bivy for your area, and you probably have may more options for tree protection in the wind than where I tend to camp. I just wanted you to know there are other lightweight options besides a poncho tarp that I feel give a much greater margin of error in stormy weather. You could always make a much larger tarp and only add 2-3oz, but for me it was a weight compromise, and keeps the tarp setup really simple.