This is one of those geek alert ones… but you really should have a look at it, it might help you control your friends and relations from trashing your Windows XP setup
Over at Mark’s Sysinternals Blog there is a recent post called Running as Limited User – the Easy Way.
The Malware epidemic has grown to Cecil B deMille proportions in the last few years. No matter how careful you are; running antivirus, antispyware, and a firewall, even a careful user can fall victim to malware (how true). Malware-infected downloads, drive-by exploits of Internet Explorer vulnerabilities, and a careless click on an Outlook attachment sent by a “friend” can trash your carefully configured system and lead to several boring (and you really don’t know how boring this can be until you have done it) hours with the Windows setup CD and application installers.
Mark Russinovich and Sysinternals have some of the best tools, Mark is the guy who identified the Sony DRM rootkit. Once you have finished reading the post have a rummage through the rest of the Sysinternals site.
Well worth it.