Well, I know that for sure, MS released a patch for Virtual PC that would let it run XP Mode (maybe others) without virtualization technology. I just read the FAQ and user's guides for Parallels and from what I gain from reading it, my impression is that you need it (at least, the latest version).
Here is the requirements list for Parallels:
It lists a procesor with VT as a "pre-requisite" which I take is a requirement, of course.
Part of the problem, too, is that my laptop only came with Win7 Home Premium 64-bit, and I don't care to buy another OS quite yet for it. I guess, from what I saw, though, VirtualBox might be one of my only choices, unless I decide to go the VMWare route, which I may have to look into. But if the price is about as much as upgrading to Win7 Pro, then I'd probably just take the upgrade from Microsoft (seeing that I don't really need the Linux support, only the ability to run WinXP).