The new ones do, but some of the older ones don't.
Also, if you put in a replacement hard drive you want one that supports locking, which Live will check for. It also checks the layout of files on the drive, so if you have an 80 gig drive for example, you want the first 8-10 gig to essentially mirror the original drive, then you can put your MAME or Media Center stuff on the optional partitions (F or G if you use Slayer's Evox setup)
If the layout isn't done properly, even if the modchip is disabled you can fail the security check. It's one way of keeping people honest when they play online
Cheaters drive me mad >