Dax0007 wrote in response to my point 14. Secure format/wipe hard disk, and replace with original disk. Repeat process. (21 Things to do when quitting work)
“When taking over a company laptop I think its a god idea just go out and buy another HD, HD kit for the laptop, & some restore cd’s for that laptop.. then setup your new harddrisk for personal use and when u do company work use ur company harddrisk.. you should be 100% safe to surf, download, and do what u want.. right????”
Maybe Dax0007. But swapping hard disk drives on a Lenovo Thinkpad is going to get awful tiring fairly quickly. The following three drawings from IBM illustrate how much of a process it is: 
(used to take me 10 minutes to swap the disks on a T41 Thinkpad)
If I still had a company laptop, I would
- set a drive password on the hard drive
- encrypt the hard disk drive with TrueCrypt.
- also TrueCrypt encrypt any “backup” drives I used at/for work.
And I’d also remind myself that anything I do while connected to the corporate network, is definitely not “safe” from scrutiny.