Well, first off, don't listen to pat...it sounds like he's havingsome sort of bad day that makes him make unsubstatiated blanket statements about other people's hardware...(/preach).
I just made the same upgrade, (from an XP to a 64 with the ASUS AV8). I haven't had any major problems yet. I agree with the Wharfster in that a minimum amount of start programs will make it faster, but that's kind of a no brainer. It is very difficult to rmote troubleshot this type of problem.....BUT...soyware could be taking up cycles, if you don't already, download and install spybot, and adware. Malware will always slow down your computer. memory setting could be a problem, but they are not going to affect the 'slugish' feeling you are getting tooling around windows. Check your power management settings and make sure they didn't default to something ridiculous like 'shut down harddrives after 3 mins'. My computer runs like crap unless I keep the drives spinning all the time.
Beyond these things and what wharf has suggested, I don't know what else to tell you.
If an argument can't be settled in one or two paragraphs, perhaps you're anal and should just let it go...