Gurney:

Having neither used nor seen the output of a keystroke logger, I can't say for certain. Articles, however, say that the software sits between the keyboard and the network card and records every keystroke made. Reconstructing passwords by looking at the page being displayed should be a snap. The answer is to scan your machine regularly and, if outsiders have access, check for unknown dongles. Also, never make payments or give out personal information by going through a link in an e-mail; enter the url (one already known and trusted) yourself, by hand.