motorhaven - 2:15 am on Nov 2, 2009 (gmt 0)

First, go into your BIOS setup and turn off booting from devices other than the primary hard drive. Then password protect the BIOS.

As to Norton, in the latest version they've really stepped up their game. Its light years ahead of previous versions. I don't use it, but many of the security reviews look upon it pretty favorably. Not only is it getting the job done, but its firewall, anti-virus and anti-spyware engines are now the fastest in the industry in most benchmarks.

In addition to guest accounts and other advice already given, run one of the freely available security audit programs for your computer. Windows has several default settings which need to be changed to secure it better, too many to go into here in a single post. Remove Internet Explorer access from the guest account, and install Opera or Firefox for the guest account to use. Install Truecrypt and create a container drive... move anything you want to keep private to that drive, then use a utility to securely wipe free space on the drive. Turn off all unused services - not only will this help secure the computer it will also boot faster. Turn off autoplay so files on a USB drive, flash memory card and CD are not run automatically when inserted. There's instructions somewhere on the net for disabling mounting of additional drive letters as well, which will offer further protection against inserted devices.

For the ultimate in protection, use a partition manager to create a bootable 10 gig partition. Use Truecrypt to encrypt your "real" partition. Both will be available on the boot menu, but they'll need the password to access the encrypted drive. Their 10 gig guest partition should have just the basic browser and that's it. Backup the drive before you encrypt it should the worst happen and malware gets on the computer and wipes out your encrypted partition. When your guests leave, unencrypt the "real" partition, delete the 10 gig partition and use the partition manager to reclaim the space.

Lastly, if you don't trust someone enough that you're concerned... don't give them access (or as noted, rent a laptop for a week).