WDS allows you to have multiple boot images. I know it can do both 64 and 32bit (if you have a 64bit server OS), but I haven't tried a 16bit boot image. WDS can also have Linux boot images as well. WinPE (what I use so far) v2.1 comes in 32 and 64bit. There is an older version, v1.5 which was the Server 2003/XP PE (available to OEMs only) and also is what things like BartPE uses. But honestly, if you are going to do this for imaging, you should check out Imagex. Its a file-based imaging solution as compared to Ghost, with is Volume based. One downfall is that Imagex won't capture the boot sector and/or MBR like Ghost does, and it only understands NTFS and FAT/32. Basically, you will find a lot of different answers to this kind of question, because there are lots of different ways to do it. And we all do things a little differently than everyone else.