I've used Symantec/Norton for many years without any problems. I've been using Systemworks 2005 for about 3 months now and like it. It's more user-friendly than previous versions. You are free to install only certain programs (e.g., I didn't install Norton Go Back -- a program which I understand can cause problems.).
They've added a new option that is pretty much like Tweakui for fine-tuning the PC settings, too.
Regarding the "bugs" posted in earlier messages regarding Systemworks 2002, I would note that the sites cited also provide relatively easy fixes for the user. Additionally, from the links posted, it does not appear that these "bugs" are critical or in any way cause damage to the end-user's computer (aside from adding a bunch of unnecessary files, which can be removed). Annoying, yes. Damaging, no. Something to consider; but not a critical deal breaker.
Overall, I haven't heard of another program with the same options and stability. I'd recommend the upgrade.