Brian,

I'm no expert but I'm pretty familiar with PCs. I use my PC partially for gaming, and hence frequently build and modify my PCs, so I generally end up reloading the OS every 1.5 yrs max. I use two HDDs, one major one and a smaller, older one. I bounce my data onto the smaller drive then wipe the larger one and reload the OS. In the interim, the smaller drives serves as a backup for my main data.

I think that over the course of day-to-day use, all kinds of software gets installed/uninstalled, etc. so yes, the registry can get cluttered, but there can also be issues with drivers, background processes, etc. Systems slowing down without any blatant spyware/malware issues may have other background processes working to slow things down. You may also have malware that hasn't been detected by the programs you are using. Have you tried posting a hijackthis.exe log?

Generally, if performance really starts to slow and/or you start getting any number of weird OS messages popping up, I nip it in the bud and reinstall Windows. Since I generally upgrade annually, I reinstall the OS each time and I've never had any major issues with XP - it's been an excellent OS. I have never tried a registry mechanic - I'd reinstall XP before trying one of those. XP also has a repair utility you can launch from setup.

Just my $0.02.

__________________
Chris
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired

"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon