I beg to differ. The term "haha" actually sounds like a person laughing, and has been used for a countless length of time as the prime indicator of laughter. Simply adding the "W" to the beginning gives it a more "cartoonishly villainous" feel to it.

As for "ROFL", there is not a single human being on this planet that when laughing makes the noise "rowfull". It is nonsensical, and completely ridiculous to post that acronym on a forum. I can understand it's use during Instant Message, but not on a message board.