its not illegal and its not cheating. it improves my edge marginally, and yes improves my hourly wage. poker is a game where you use all (legal) means possible to increase your edge against your opponents.
right now the rules on most major sites are that you are allowed to use statistics programs(like pokertracker.com ), but your are not allowed to share databases. bots, colluding, chipdumping and a few other nasty practices are not allowed either.
there are lots of sites which goes around this(database sharing) by providing highlights from the data, http://www.sharkscope.com/index.html being the most popular (you can try it for free/no-signup if you want). if you are intrested in which programs are allowed at the site you play just check the FAQ at the site you play. if you dont like the rules dont play on that site.
i just wanted to share that the 8core is useful for me.
Ah my bad. It sounded like you were reading other peoples' hands and cheating that way.