Yep, as an advertiser and publisher I have to say that most webmasters are slowly ruining adsense. The clicks most sites send to advertisers really do very little, that's why click prices are depressingly low across most topics.
Thanks for the replies all, some very informative posts, and amusing ones as well I wouldn't even think of trying to scam the system, was just worried as i've heard of many people losing their accounts for no apparent reason, I live in a house with 4 other connected pc's, so was just worried about any family looking at my sites and clicking an ad - i've given them all a lecture about it today though anyway, hehe. Hopefully google has, as some people have suggested - a very advanced fraud detection system, that will protect honest publishers as well as it does the advertisers. Aslong as its not just a crude IP based system!