aye, you bring everything you normally play on and use (and an extra removable drive or easy swapping).
The only thing you don't need to bring is an Ethernet cord (it should be already set up for you to sit down and plug in, if it's an organized party)
most places also have a share for you to either dump files or take files, depending on what you need to run the game

This LAN party is something that my company puts on about once every 2 months. It's a pretty cool deal since we get to use one of the buildings and do whatever we want (minus drinking-liability the company doesn't want).
It's slowly building up the numbers of the year and a half I have been going. They also started doing a loyalty thing so if you had gone to the previous LAN parties during the year, you were in a basket that they draw for prizes at the end of the year.
The top 4 prizes this year were:
1)gamer rocking chair thing with speaker/hookups
2)the logictech gamer (L15?) keyboard
3) wii
4) 360
I had the option to take another prize, halo 3 game, but I opted to pass so I was still available for the big prizes...it didn't work out and I didn't win crap...that's the breaks I guess.