LOL, mistook it for a 5D, there's quite a difference between those too cameras.
I may get both the wide angle and tele lenses in the summer, just want to get used to the camera first. The 220EX is perfect size for the camera, it does add quite a bit of weight, but you soon get used to it. It's much more powerful than the internal flash, as expected, and gets the exposure. I agree though it's quite big when compared to the camera. I've seen pictures of the G7 with the 580EX flash mounted on top, now that really does look stupid, not sure how you'd be able to hold the camera.
If the wide angle lense you've got the canon one, or a different make. I've heard the canon one is much more heavy than other makes, but it's much better quality as well.
If I was you, I'd definately consider getting an external flash, the 220EX is the right size, because when the wide angle lense is fitted, it blocks the internal flash, which I'd find a pain.
BTW, there is a picture of my camera with the flash on top, doesn't look too big.
