Problems dualbooting Ubuntu because of UEFI

It sounds like Windows was installed in EFI mode. (Evidence: You refer to a "BIOS reserved area," by which I believe you mean a BIOS Boot Partition, which is valid only on GPT disks. Since Windows will boot from a GPT disk only in EFI mode, Windows must be installed in EFI mode. This analysis could be incorrect if I'm misinterpreting what you mean by a "BIOS reserved area," though.) A BIOS Boot Partition in Linux means that Linux is booting in BIOS/legacy mode. The two, as you've correctly inferred, are awkward to switch between on most systems.

There are several possible solutions. This list is not exhaustive:

• Use your firmware's boot manager -- All modern systems offer a built-in boot manager, usually accessed by hitting F8, F10, F12, or some other key at boot time. It pops up and gives you boot options. On most UEFI systems, those options include both BIOS/legacy and UEFI boot options. Thus, you can select your OS by using this feature. Some UEFI implementations, though, provide such a poor built-in boot manager that this isn't a practical option, or it may not work at all.
• Install a Linux EFI boot loader -- Ubuntu uses an EFI version of GRUB 2 for this, in the grub-efi package. Installation will be tricky, though; unless you're booted in EFI mode, installation will be incomplete, so you'll need to use an EFI-booted emergency system to do the installation. There are other EFI boot loaders available; see this page of mine for details. (IMHO, GRUB 2 is the worst of them, so alternatives are worth investigating.)
• Use rEFInd -- The rEFInd program, which I maintain, is an EFI boot manager that can launch an EFI boot loader or (on many, but not all, UEFI systems) a BIOS-mode boot loader. You can install rEFInd from Windows and then try editing its refind.conf file to add hdbios to its scanfor line. If this works, you'll then get a rEFInd boot menu that shows Windows and a generic option. The generic option will boot your BIOS-mode GRUB. If you installed Ubuntu 12.10 or if you're comfortable compiling your own kernel, you can use rEFInd to boot Linux in EFI mode, too; rEFInd is one of those alternative EFI boot programs noted in the previous option. You'll almost certainly need to adjust the configuration a bit to boot Ubuntu in EFI mode from rEFInd, given your current setup. See rEFInd's documentation page on booting Linux for details.
• Reinstall Ubuntu -- You can wipe your Ubuntu installation and re-install it in EFI mode. This is the easiest option to describe, and it may be the easiest to do; but you'll learn the least doing it. It's also not guaranteed to work; EFI-mode installation still has quirks and pitfalls, many of them system-specific.
• Revert to BIOS -- You can wipe the hard disk of all data and re-install both OSes in BIOS mode. This is probably more effort than it's worth, and the Windows media you can create from files on your Windows installation may not even support it.