How to know if my BIOS supports UEFI?

There will be an extra UEFI partition on the hard drive, It may be hidden, if you can get a look at the files in the partition there will be some with an .efi file extension.

Different manufactures label the partitions differently, mine is labeled "HP_TOOLS"

I agree with William, all the new laptops I have seen in the last 2 years have UEFI

EDIT:

Another way may be to look in the C:\Windows\Boot folder for an EFI folder, it does not exist on non efi bios system's, You may have to unhide system or protected folders in folder options to see this folder.

I am having problems confirming this information, but, I have personally not seen a laptop released within the last few years (non atom and latest technology) that was not EFI.

The best bit of advice I can give is to write down the BIOS version/serial/manufacturer and try to Google it and see what you can find out.

If EFI/UEFI meant extra partition on the HDD, this would imply that UEFI based machines can't boot diskless, and yet they can! You can't rely on that to determine if a machine is (U)EFI capable. Furthemore, HP_TOOLS does exist on non-UEFI based installations, it is created by some extra tool (ProtectTools, BIOSUPDate, Sparekey etc), so even if you do have HP_TOOLS on your HDD, it does not mean your PC is UEFI based.

Follow Computer> C:(or your Local Disk)> Windows > Panther

In the folder look for the file called setupact. Open it and hit Ctrl+F to find the string:

Callback_BootEnvironmentDetect: Detected boot environment:

It will be either BIOS or UEFI.