Here's a follow-up post regarding the performance of the older Nikon 300mm ED lens with a 1.4x Kenko PRO teleconverter. The results are often sharper for me WITH the teleconverter than without. I love the contrast this low-price lens combo offers. It's still not quite a Nikon 500mm, but it's still pretty sweet.
All the shots are tripod-mounted, with my hand loosly draped over the top of the lens to dampen the vibration of the D70 and D200 (both used in these shots). I try to keep the shutter speeds above 1/125, though some shots dip to 1/80 sec., a realistic set of results with a sturdy ballhead from Kirk Enterprises.
98% of these shots feature some fill flash with SB units as well, usually at around -2 EV...just enough to make sure the feather detail is all revealed. F-stops will range from f4 to f6.3.
Red-bellied woodpecker:

Black-capped chickadee:

Tree swallows - mating behaviors:

Song sparrow:

Mid-phase house finch:
