So Vista is coming and the PC manufacturers are hoping to grow fat on your largess as you upgrade everything to stay fashionable. But you don't have to wait for Vista!
Maybe you laugh at my intolerance for Windows sloth. You've got an dual-processor or maybe an AMD64 and you've got cycles to burn baby! So how can you make it run slower (but possibly prettier) ?
Use more powerful themes: take a look at the Stardock site for info on WindowBlinds and other desktop themes or shells, some rather radical (and some just radically unstable).
Run lots of .NET and Java applications: I love Java but both .NET and Java are semi-interpreted languages. Pick one or two favourite applications, and try to stick to either Java or .NET because that way they will share more code in memory. There are lots of useful Java apps, the only .NET app I ever used was SharpReader and I've switch to Sage in Firefox for reading RSS feeds so it's goodbye to .NET from me (that's another reason why Firefox is cool; once you are running the Mozilla platform (Gecko, etc.), your extensions (which are really mini applications) share the code in common with Firefox itself. It's a pity there isn't a user-oriented Java application that achieves the same (though tools like Intellij IDEA, Eclipse and JEdit do pretty well at providing an application platform for software development extensions).
Use Windows Desktop Search and Google Desktop Search: I'd love to be able to search my desktop, but I don't want to run even one of these things because they are so slow (maybe if they would run overnight and then shutdown my desktop when they've satisifed themselves that they've probed every nook and cranny). But if you've got cycles to burn, use 'em both and compare the results. Meanwhile, I'll continue to use baroque folder structures (which I continually reorganise, increasingly using tag-style names rather than old-fashioned hierarchies) to hoard my precious bits and bytes.
Run lots of anti-malware programs: there are so many free anti-adware, anti-spyware and anti-virus programs out there, it's easy to give up whole chunks of your CPU to try to achieve safety and privacy. My recommendation: choose one or two quality apps and dump the rest. But if you like the warm fuzzy feeling of having an army of anti-malware tools attempting to control the horizontal and vertical on your desktop, go ahead.
Use a local mail client: Gmail convinced me that a web-based client could do what I needed, so Thunderbird now languishes unused (except for occasional "backups" of my web mail over POP3). Outlook Express - don't make me laugh. So now Google provides the hard drives and the cyles to store and search my mail. But by all means, run a local mail app (or two) - and of course you might have to anyway for very private or work-related mail.
Use Windows Media Player: Yes, WMP is a charming beast. You'd be better off saving memory and CPU by running Winamp. But dash it all and don't spare the horses - use the latest and greatest (well, largest) WMP and while you're at it, use GForce (actually though, GForce is so pretty that it doesn't matter that it likes your CPU; you won't be doing anything else but watching the darn thing go through it's fractal gymnastics).
So give that little lot a try and let me know how you get on. If you've still got any CPU to spare, drop a comment here and we'll see if we can find anything else to keep your desktop busy.