If so I will probably have to pass, as I know little about it.
However my final contributions, (probably), note;
1] Startups, around 7 or 8, might be 10. It only needs one to slow down startup, if that is also an issue.
2] Services. I have no idea with this being Vista, but 100 seems excessive. BlackViper's guide may help;
3] Nortons, What Nortons application do you have? Some suites will 'do everything', and in the process slow processing down. As an example, you say EC has been running for 5 hours, (even more now?); is Norton interrupting and checking everything it does? Since the registry is the heart of the OS, anything that attempts to access and/or change the registry may be being flagged by Nortons for double checking.
4] Reputable sources. Your choice here, but all I will say is, I have never used any of the those commercially available, "Fix All" registry cleaners available for XP, and my own (5 year old) system still boots up in around a minute, and has no performance issues. But then, I choose not to mess with the registry directly and I allow my anti-malware utilities to protect it, and run CCleaner to clean out temp files and occasionally run its registry cleaner. I last ran its registry cleaner 4 months ago.
5] On a new machine, relatively new and unused OS, performance issues do not point to the registry.