Okay, so sounds like the issue is getting Win7 installed on your particular hardware, so it's not really a multiboot issue (at this point, anyway).
Your first step should be to download the "
Windows 7 Upgrade Advisor" from Microsoft. Boot into your existing XP and run the Upgrade Advisor. It will tell you what hardware or software Win7 will have issues with. If it's going to have driver issues with some of your hardware, you'll need to research that beforehand and see if you can find suitable drivers yourself. In many cases, if Vista drivers are available those will work. What you're mainly concerned with are your internal devices (video, audio, motherboard, etc.). You can choose not to use peripherals or software, but non-functional internal devices could render Win7 a "no-go" on that system.
If it doesn't look like there are any real "show-stoppers" in the Upgrade Advisor's report, then you should proceed by separating the parts of your project and tackling them one at a time. IOW, take multibooting out of the scenario for the time being and work on getting Win7 installed by itself and working properly with your hardware.
Since you've already installed BING, temporarily deactivate or uninstall it so you're not multibooting. IIRC, you're using multiple hard disks, so remove any other hard disks (or disable them in the bios) except the one that Win7 will be installed on. If the disk you are installing Win7 on has other partitions, hide those partitions and make sure the target for Win7 is the active partition. (You can do this with ptedit or by booting from the BING CD and going into maintenance mode from the CD.) Now you've got a simple one disk, one partition system for Win7 to deal with.
Are you trying to upgrade Win7 on top of (a copy of) an existing XP installation? I don't recommend that. Do a clean install instead. The Win7 upgrade DVD can do a full install, so boot from the DVD instead of launching the DVD from within XP.
Refer to
Paul Thurrott's site for some screenshots. When you get to the first screen in Part 2 (
"Which type of installation do you want?"), select
"Custom (advanced)". Your disk is already partitioned, so the next screen (
"Where do you want to install Windows?") should show your partitions. If you made it active earlier, the target partition for Win7 should be called C:. Make sure it is selected, and click
"Drive options (advanced)". Format the partition so Win7 has a clean slate to work with. Then let Setup continue with the bulk of the installation.
When you get to the bottom screen in Part 4 (
"Type your Windows product key"), leave it blank and
uncheck the box,
"Automatically activate Windows when I'm online". (I recommend getting everything working right before activating. As Paul Thurrott mentions elsewhere, delaying activation can also avoid activation failures due to upgrade vs. clean install confusion.)
When Win7 is finished installing, manually install any drivers you need to take care of yellow question-marks in Device Manager.
Once Win7 is installed and working properly, you can activate it, reinstall other hard disks, reinstall BING, and let BING control which partitions are hidden or visible.