I am very keen to try Digital Blending & would it be possible with Aperture 2

Hi,
Read the tutorial on Digital Blending & High Dynamic Range [HDR]. My reading suggests that RAW images are not possible for it.

I own Aperture 2 as my photo manipulation software to use in my Mac computer. I hence shoot my photos in RAW format in my Canon 40D.

I wonder if I could do digital blending/HDR in my Aperture? I find if I take photos in jpeg the Apple's Aperture software would not allow it to be modified/edited

Is there any free programs available for HDR/Digital Blending [I paid over 100 bucks for Aperture 2]

Regards