I want to free up some space on my HD. I have some files named file0000.chk, file0001.chk and so on. They are over 500MB. What are these? Can I get rid of them? Also what about the pagefile.sys and the Win386.swp files? Are they needed? Which can I delete without giving myself a problem? Which ones have to stay? Thanks in advance.

The .chk files can be deleted. The Pagefile and Swapfile are in use so you can't delete them while windows is running. Even if you did, Windows would immediately recreate it.