If you're dual-booting to Windows and Linux, then you will almost certainly be using Grub to do that. Grub is rather more flexible and configureable than Windows, but a different "skill set". You do need to mess with coding and stuff, though.
I didn't get as far as multiple-boot with Linux, XP and Win 7 so can't comment on how that works, but I doubt it would be problematic.
I got fed up with (year-ago) Linux getting the total hump when my graphics card popped its clogs and I replaced it with a later version from the same manufacturer. Windows hardly noticed the change and carried on working, while Linux (all versions except Fedora) reverted to a DOS box with several pages of gibberish code error messages. That's the problem with compiled kernels if the slightest thing changes in the hardware.
That happened about a day before I downloaded Win 7 Beta, so I wiped all the Linux partitions, merged them, and put Win 7 on there. No regrets!