Can't install Windows 7 Ultimate x64 on a Dell XPS 720 - Please help

I just bought a Dell XPS 720 Extreme edition.

Specs:
Intel Core 2 Quad Q6600 2.4ghz CPU
8 GIGS of RAM
Brand new EVGA NVidia GeForce 630 GT GPU
BIOS is up to date.

I followed the instructions on this website about leaving just 2GB of RAM in while installing the x64 version of Win 7, but still can't get it to work. I've installed OS so many times and able to install Win 7 on a 2006 XPS 400 which I am using now and runs like a champ, but will crap if I can't get it to install on a much more powerful machine that is a 2008/9.

The message I get with a black screen is "No bootable partition in table"

Then I created a bootable USB drive to install Win 7 and all I get is a blinking flat cursor _ I went into the BIOS to change the boot sequence around to USB first as well.

I know the computer will boot up Win 7, I threw one of my back up drive with Win 7 on it from my XPS 400 machine and it boots up the Windows rotating logo until it BSOD due to the obvious conflict with the drivers.

Can someone please help me with any other suggestions? I would hate to sell this computer after buying parts for it and professionally cleaning it out.

Thanks in advanced!

I can't even get to PIC 2 (press any key to boot from cd) in that link you sent. Goes right to the No bootable partition message.

That's correct, it doesn't even show me that message to press any key. Let me go try a couple of things and will report back again.

Thanks for trying to help, Kaktussoft. I'm usually able to get my problems solved here; great forum.

The XPS 720 can support up to 8GIGS if using 64 bit of windows. It shows 8 gigs in the bIOS.

For some odd reason, my computer is not recognizing the install DVD or the USB. Attached is what I get when trying to boot and install from the USB drive.

If I don't put in a disc or the USB, it just boots to the WinXP MediaOS fine.

**UPDATE**

The two DVD rom drive that originally came with my computer was DEAD. I took out an old drive and hooked it up. Went into the BIOS to change it to boot first then the HDD.

Restarted the computer and hit F12 for the boot menu and chose to boot with the DVD and then windows 7 x64 installed fast and easy.

Thanks again for the help on here guys.