...that particular procedure was originally written for Windows 98.. Some of the items you are referring to are actually discussed further down in that specific topic area.. Generally, the answer is Yes, you can delete all Files and Folders with a .tmp file extensions, BUT there is one caveat that I can think of. With Windows XP, there is a "Lastgood.tmp" folder that is created and used if you ever need to use the "Last Known Good Configuration" restore option. Because of that, although it won't "hurt" anything if you delete the "Lastgood.tmp" folder, you may not be able to restore back to "Lastgood" if necessary. It's your choice. I would keep it if I had plenty of space. Besides, the "lastgood.tmp" folder can sometimes be difficult to delete because it's normally being "used" by Windows.
In Windows 2000 and earlier, there shouldn't be a problem with deleting Folders with a .tmp extension.
Likewise with the .chk files. It won't hurt anything to remove them but for Windows XP, the common .chk files in Windows XP are normally "edb.chk" files which are recovered file fragments and are frequently used as "checkpoints" for various programs. It's a personal choice on these particular files as the .chk on Windows XP are extremely small files and if you've only got two or three of them, it's not that important to clean them out. On Windows XP machines I LEAVE the .chk files where they are. On Windows 9.x and ME, I delete them as they can become numerous and large.
Hope this helps.