The main reason I need to install Windows is to play Guild Wars 2, a game that has in the past run well on XP my MacBook at lowest settings, but with unacceptable framerate drops while playing in OSX using the game's official Mac client. Since this official Mac client itself uses virtualization and still suffers from perfomance issues in OSX, I'm sceptical about virtualization and would prefer to natively run Windows.
Well, then you are either going to have to revert to Snow Leopard, use virtualization, or stop playing. I very much doubt Apple will provide support for a dead OS.
However, I don't know if there are any possible workarounds.
It is also possible that the game was "ported" or "emulated" on OS X and virtualization might provide better performance. As I stated, VB is free. No harm in trying. I would imagine you should get better performance out of one of the paid VMs, but again, I don't know.
UPDATE: I'm happy to report that Windows 7 64-bit does work perfectly with Boot Camp on my machine!
To help out anyone else who might need to install Windows 7 64-bit on their MacBook, I will outline what I did below. Please note that the following instructions worked for me on my system (MacBook 5,1 Late 2008 Aluminum Unibody 13", Intel Core 2 Duo 2.4 GHz, GeForce 9400M GPU, 8 GB RAM running OSX Mavericks and Boot Camp 5.10); I don't know if they will apply to any other MacBook models. Since my MacBook comes with an inbuilt DVD drive, I didn't need to create a bootable USB version of Windows; I simply used a (legitimate) Windows 7 Home Premium 64-bit installation disc and product key.
1. Back up your important files on OSX using your favorite backup method.
2. Download the Boot Camp Support Software version 4.0.4033 here: http://support.apple.com/kb/DL1630. These are the drivers you need to install in Windows 7 to get your OS to recognize and use your hardware.
3. Unzip the zip file from the previous step and copy the contents (the folder named "BootCamp") to an empty USB stick that is FAT-formatted (to format the USB, you can use Disk Utility in OSX.)
4. Safely eject the USB once the folder has been copied onto it.
5. Insert your Windows 7 64-bit installation disc into your DVD drive.
6. Start Boot Camp Assistant.
7. Uncheck the box that tells you to download Windows support software (you have already done so; it's on your USB stick.)
8. Proceed with partitioning. Once finished, the computer will restart and Windows 7 installation should begin.
9. Hurdle 1: When the installation process for Windows 7 started up and the program asked me which partition I wanted to install Windows on, it wouldn't initially allow me to select the Boot Camp partition. I had to select that partition and click on "Format" first before it allowed me to install Windows onto it.
10. Windows 7 installation should proceed normally.
11. Once you have loaded into you Desktop, it is time to install the support software (i.e. drivers) from your USB. Insert the USB and copy the BootCamp folder onto your desktop. If you don't have an external mouse, pressing Shift-F10 will do the the same thing as right-clicking.
12. Hurdle 2: After copying the zip file containing the Boot Camp drivers to the desktop, I tried installing them via the setup file but got the error message "Boot Camp x64 is unsupported on this computer model". This is a LIE! To fix this, I first disabled the User Account Control (Start>Control Panel>User Accounts>Change User Account Control Settings>set to "Never Notify.") Then I rebooted. After rebooting, I navigated to the zip file BootCamp>Drivers>Apple>BootCamp.msi and it installed all the Boot Camp drivers perfectly. I rebooted again as per the installation process requirements.
13. Run Windows Update to get all of Microsoft's updates, including Service Pack 1 (took me hours...)
14. Hurdle 3: After updating my NVIDIA GPU (GeForce 9400M) driver to the most recent driver version (334.89 WHQL) via their automatic update program, I lost the ability to control my screen brightness (pressing the brightness keys brought up the brightness level indicator, but did not affect the actual screen brightness.) To fix this, I had to do the following:
14a. Go to Control Panel>Hardware and Sound>Device Manager>Monitor>Right-click Generic PnP Display and DISABLE it.
14b. Open regedit by typing "regedit" in the Start menu search bar.
14c. Navigate to the following sub key: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/Class/Video/0000
14d. Create a new DWORD named "EnableBrightnessControl" and set its value to be 1.
After having done all this, Windows 7 with Service Pack 1 64-bit works flawlessly on my MacBook. I'm also happy to say that Guild Wars 2 runs quite well on low settings, which was the whole point of going through this.
I hope this thread is useful to others.