The whole deal is really a lot more trouble than it's worth. If the OP doesn't want to go the VM route (the easy way), and doesn't qualify for downgrade rights from MS, then I'd suggest doing some serious, hard core searching on how to accomplish it. On this forum, our advice on running XP is limited to XP Mode, which is a benefit of having 7 Pro or above. There are plenty of multi-OS & even dedicated XP forums that has many members willing to help. It would defeat the purpose of this being a Windows 7 Forum to introduce a lengthy thread with several pages of advice on doing a XP install on modern hardware, which may not even work at all.
Still, that's going to be a ton of work. I looked into doing it myself, and even sought advice on both the TechNet & Microsoft Answers forums. Any computer that's been built within the last 2 or so years, drivers are going to be a major hurdle to overcome. It was a project that I wanted to do, create a dual boot between XP Pro 64 bit & 7 Pro 64 bit, but all that I ran into was brick walls & dead ends. I gave up on it, and accepted running it through VirtualBox, which runs perfectly fine.
My suggestion would be to build a computer with older/surplus parts (Computer Geeks has plenty of these), or buy a refurb (or new, if one can be found) PC with XP 64 bit preinstalled. Computer Geeks has a wide range of refurb PC's at low prices, and most everything needed to build a XP based PC.
http://www.geeks.com/
Here's also a brand new one. The 64 bit versions are hard to find, but this seller has 200 of them.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370482330729#vi-content
Best of Luck,
Cat