Analogies fail to grasp the full extent of situation.

However, compare this cleaning of your PC to getting the office cleaner to do a vacuum and empty the rubbish bin (delete files) and a spray and wipe (clean the registry).

Sure, there's good in cleaning your office, but a spray and wipe means that the desk must be uncluttered or the cleaner will unclutter your desk for you. Once someone else unclutters your stuff, you don't know where it is. Ditto with the vacuum cleaning. You open the PC and aren't meticulous in laying out all your screws. One of them drops onto the carpet. Or you've got this snot sized phone flash/memory card and that drops onto the carpet. A very caring cleaner might hear your screw being sucked into the vacuum cleaner and might spot that precious memory card. A less caring one or one in a rush, will simply suck and throw out the rubbish.

As I said, analogies fail to describe things so I'll leave this analogy at this point.

Specifically to products like CCleaner, they reverse or have to reverse engineer what is deposited on your PC, to sieve out the good .dlls and registry entries from the bad or from the neutral. Although they may not state that they are beta, in effect, they are always in beta - as they learn of undercleaning problems or overcleaning problems, they will increment their version and improve their performance.

The fact remains, that products like these will always have the potential to underclean (not deleterious but does not resolve your problems) or overclean (damage your system).

In security, it is always better not to get invaded than to get invaded and clean up what you think has got through.

That's the big deal with Vista. WXP is quite robust for what it has to do - however, it has potential vulnerabilities which are as yet undiscovered. In Vista, they re-engineered a fair bit to start off with the premise that they could have less opportunity for vulnerabilities if they engineered the software better. In doing so, they had to break device driver compatibility and for good measure, foist the Linux Ubuntu GUI like UAC on end users.

So, what should you do? Let gunk just accumulate? No, I'm not espousing that.

Take your budget for maintenance time and assign it with more productive activities.

1. Make routine backups of your system volume - if you have the now ubiquitous USB external hard disks, the presence of a Maxstor or Seagate hard disk allows you to use their cut down, free version of Acronis.
2. Make even more regular System Restore Points. Also, Windows XP Pro's native backup utility can back up system state and ConfigSafe will do the same for Vista (not fully exercised yet)
3. With regards the Internet, think about doing things in a virtual machine (VirtualPC or VMWare) or put on some protection (ShadowStor ShadowProtect)