XP Home will boot up fast if you don't have a lot of programmes set to run on start up, and of course completely depends on the speed of your PC aswell. If you have a slow, tired old-tech processor and chip with smallish (less than 512) RAM, then no it won't be super fast comparred to a new PC with a big powerful, new-tech pro/chip set up and oodles of RAM.... I run XP Home (did run Pro but reinstalled with Home cos I couldn't find the Pro disk ) and it takes a minute, sometimes a little bit more - I have a 2800mHz P4 chip with 1.5gb of RAM, but I have about 10 programmes that begine to run on start up aswell so loading them all and hooking them into the net takes another 30 secs or so. I can use it in this time, but it won't be as quick or responsive of course.

Oh and XP Home will boot faster than XP Pro as XP Pro always wants to check to see if it is on a network, or if a network is available for it, and does another bunch of stuff while booting aswell

As far as XP64 goes, Dan is right and it will only work on 64bit systems, which are very new and full of bugs and gremlins at the mo - seems so far that about 60% of regular programmes and downloads etc don't work with XP64 as there aren't any 64-bit drivers ready for them.....