This can be a touchy subject with many people (as is the whole PC vs. Mac argument which IMO should be laid to rest). The few experiences I've had in the past with the 'mac bashing' usually comes from jealously or poor attempts at trolling. I was at a LAN party a few years ago and my friends wife brought her iMac with her. While we were waiting in a line to check in a few guys with a video camera, probably thinking they were funny, walked up to her started harassing her by asking her what games she plays on it. After they realized they weren't getting any responses from anyone, they moved on and no one else bothered her the rest of the weekend. None of my friends I attend LAN parties with act this way, so try not to generalize that 'PC gamers' are also Mac haters. Don't let a few bad apples spoil the whole bunch (I love little Mikey).
I have Mac which I enjoy but I also have a nice custom built desktop that I use for gaming. When I go to large LAN parties I don't bring my Mac I bring my desktop - because it runs games a lot better than my mac. I also don't have network problems or miss-configurations, etc. I'm very tech savvy and keep all of my machines running at tip-top shape. Also, I don't mess around with any of that water-cooling bit, I've seen too many 'accidents' over the years and figure in the end it's not worth it (sorry I digress).
A personal pet peeve I have is people who bring any computer (PC, Linux, Mac) to a LAN party and don't actually use it for gaming. I've seen people spend a whole weekend watching anime/movies, or editing photo's in Photoshop, or just listening to music. If you're going to pay money for travel, hotel, LAN entrance fees, why spend the entire time doing something that you could easily do at home. Recently due the demand that many games require a internet connection (*cough* MW2), many LAN parties now have internet access. Because of this, I've seen people spend the whole weekend playing World of Warcraft, suddenly many people realized they wouldn't have to miss their weekly 'raid' all hoped on - reducing the number of players in the other games. I even noticed one person who spent the whole weekend fishing in WoW, hope he caught a delicious bass (bad Napoleon Dynamite reference).
Like I said, it's a personal pet peeve of mine, to each their own right?
Regardless, game on!