I think Artic silver is probably good stuff but has a lot of commercialism tied to it. I work in an engineering enviornment and we use this stuff (120 series) for all types of applications that certainly exceed any PC application.
Whenever I get fake gimmick credit cards in the mail, I keep them and use them to spread on the Arctic Silver. It works pretty well, and I take a really long time making sure it's right and doesn't ooze out all over the place.
All you'll wanna use is about the size of the graphite showing in a finely sharpened pencil. That might even be too much. Just enough that when you spread it, a little of the color is still visible but you can't very well make out any lettering on the die.