As far as I know you can install any version 32 or 64-bit. I've never installed either the server or 64-bit versions. I have only installed the 32-bit client.
Now all this said I suggest you forget about Boot Camp. Just create your two partitions using Disk Utility. Install the Linux distro on the second partition using the LiveCD (you must boot from the LiveCD, obviously. Download and install rEFIt from
CNet Downloads or
MacUpdate. This is a specially made bootloader that will automatically let you boot either operating system. There is no geeky configuration required unless you wish to make special modifications to how you will use rEFIt, but I suggest reading the documentation first (it's online, but there's a link in the rEFIt folder.)
If you want to run Windows, too, then create three partitions and install Windows directly onto one of them. Reserve the first partition for OS X.
Before installing any other OS you will need to use its formatting tool to reformat the partition on which you will install it. Linux usually does FAT32. Windows can be NTFS or FAT32.
