Have you used either of these systems? Ridden an Erg video? I'm lucky there is a very well-run CompuTrainer center in town that runs structured programs through the late fall into early spring, so I've used both straighth CT (probably the lamest user interface in the world but it actually works) and Erg video in group settings (everything from fellow recreational cyclists trying to get better to competitive racers and tri-geeks). CT works well, but there are a number of competing systems out there or in the pipeline; depending on your price point and needs, they may be preferable. The least expensive seems to be one of the Kurt Kinetic trainers (known & stable power/speed profile) coupled with an add-on sensor and Trainer Road software.
dcrainmaker has reviews of several of these systems and has more in his pipeline; if you have not checked his site, definitely do so.
Golden Cheetah is an open source (I think) free power analysis software. Has many features of Training Peaks and the stand-alone WKO software. I've been using it for several years. I have a PowerTap wheel, and I use the power & HR data from outdoor rides and indoor; the indoor sessions helps me calibrate how I do in a controlled environment vs. the road. You can also use Training Peaks free on line web site, and other sites (Strava, Garmin Connect, maybe the MapMy-whatever) are adding power and history data so you can analyze and track performance over time.
None of these tools will make you faster without alot of work on the bike. A friend who is a successful Masters TT racer has never used power, GC, CT, or Erg. He has the discipline and experience to train without it. But if it motivates you, sure, why not. I geek out on the numbers (that doesn't make me faster, either). I do have a much better idea of where I do well, by how much, and how to get better. Recently, I've tried ignoring the power display in real time to work on my mental aspects; I tend to ride the numbers too much, so what I "know" my max was becomes "what my max is" even if I could go a bit harder.