After using Windows Vista Ultimate Edition for a few minutes, I noticed it seemed really sluggish. This didn't make sense since I had used it on even more resource challenged test PCs and it didn't seem so slow on those PCs. Looking at the system's task list I could see something named MSKDETCT.EXE using up almost all the CPU cycles. What the heck is that? It is part of McAfee's SpamKiller product. But, wait, I have never bought or installed McAfee SpamKiller! Ah, but I had bought and installed McAfee VirusScan 2006 in Windows Media Center Edition before upgrading my cheap PC to Windows Vista. However, McAfee's several-times-a-day pop-ups asking me to upgrade to one thing or another (including McAfee SpamKiller if I recall correctly) annoyed me so much that I uninstalled it and replaced it with Grisoft's AVG Free Edition. But, it looks like the uninstalled did not uninstall everything. It left an entire folder with what is probably McAfee's SpamKiller buy-me buy-me ad pop-up. It had apparently laid dormant after being uninstalled under Windows XP Media Center Edition but came to life after upgrading to Vista.
I manually deleted the McAfee folder under Programs. Then, I used good ol' MSCONFIG (yep, it still exists under Vista) to remove McAfee SpamKiller Detect from the Startup services list. Vista became much more responsive after this minor system surgery.