Parallels, VMware Fusion, VirtualBox
I'm running an RC of Win7, which M$ now considers "illegal," in VirtalBox and find VB to be much faster than either Parallels or VMware Fusion. Of course, I haven't upgraded either of them because they want more money. It *may* be that it's faster because it's Win7, but I doubt that VB's faster startup time has anything to do with that. In any case, this is why I wanted to put a "copy" of my BootCamp XP installation in VirtualBox.
Over the week-end, one of the things I tried was following the instructions in the link you gave me (I'd found it by googling,) picking up where it turned to VMware, but ultimately that didn't work giving me error messages that said something to the effect that the virtual file couldn't be opened or booted or some such because of error(s.) I actually have both the connection to BootCamp in VMware Fusion (v 2.0.7) and a freestanding virtual 'machine' of XP, but neither one of those comes up as fast as VB's, and they are both having problems, albeit different ones.
I'd very much like to be able to create an XP installation in VB from either BootCamp itself or from the XP virtual 'machine' in Fusion (even though that one isn't as up-to-date) so, yes, if a VB user out there has ideas on how to do so, error-free, I'd welcome the input. In the meantime I'll have a look at Ingo's links. I suspect some of them will be to things I tried already.
Also, I'm intrigued by your mention of WinClone. It would be so nice if I could use that, but how?