Do I need to re-install windows 8 to enable UEFI?

I know that UEFI provides for much faster boot up speeds, but as of right now it is disabled in my BIOS. Should I enable it and it'll switch over auto-magically?

Firstly: note that while UEFI can provide faster boot times, it doesn't automatically do so; it depends on the firmware in question.

Secondly: yes, you need to reinstall Windows if you want to switch to UEFI. Windows is installed in UEFI mode only if you boot the install DVD in UEFI mode. You may also need to reformat the disk, because in UEFI mode Windows requires GPT partitions.

(Or, at least, that's how it worked with Windows 7. I wouldn't expect this to have changed in Windows 8 but I can't be certain.)

This article describes how to convert a BIOS-mode Windows installation to boot in EFI mode without re-installing. I'm afraid the procedure is a bit too long for a full summary here, but basically it involves backing up your data, converting the partition table from MBR to GPT non-destructively using GPT fdisk, adjusting your firmware settings, creating an EFI System Partition (ESP), and installing the Windows boot loader on the ESP.