Is is always completely OK to delete ".tmp" files?

Using a file locator utility, I found the following files, for example.

C:\WINDOWS\SET29.tmp (22 KB, 3/30/2006 3:03:56 AM) C:\WINDOWS\SET2A.tmp
(11 KB, 3/30/2005 10:54:06 AM) C:\WINDOWS\SET3.tmp (1,019 KB, 8/4/2004
3:00:00 AM) C:\WINDOWS\SET4.tmp (1,061 KB, 8/4/2004 3:00:00 AM)
C:\WINDOWS\SET8.tmp (14 KB, 8/4/2004 3:00:00 AM)
C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\Tem p\ZAP1BE.tmp (11/28/2007
12:01:26 AM) C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\Tem p\ZAP258.tmp
(4/10/2009 8:10:13 PM)
C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\Tem p\ZAP363.tmp (4/10/2009
8:16:01 PM)

I note that these files are in the WINDOWS directory.

Are there some .tmp files that should be left alone forever? Are there any
precautions to be applied before deleting every single .tmp file on the hard
drive?