Recommendations on a cheap telephoto lens for birds?

[masp]

What are the lighter lenses that I can still expect to get decent detail with? I'm also considering using a slightly shorter but faster lens with a teleconverter if that might save me some weight and cost.

How do the shots from slrgear.com's review of the Olympus 70-300mm f/4-5.6 look? Potentially it has a 600mm reach, or more with a teleconverter, and is not much more than two pounds with a four thirds or micro four thirds camera. They're just small jpgs though, so maybe not the best samples.

http://myolympus.org/document.php?id=16050
http://myolympus.org/document.php?id=16025
http://retrent63.com/TP172568a.jpg
http://retrent63.com/TP172604.jpg
http://retrent63.com/TP292881.jpg
http://retrent63.com/TP292884.jpg
http://retrent63.com/TP292906.jpg
http://retrent63.com/TP222690.jpg

Edit: Sort of answered my own question when I stumbled upon the Canon EF 70-200mm f/4 L USM Lens at http://www.the-digital-picture.com/R...ns-Review.aspx. It seems to get good reviews at slrgear.com too. Aside from it's 25.2 oz weight (though relatively light) and the fact that the white L series design screams STEAL ME, it seems like a nice bargain.

Further research had me looking into at Nikon's 70-200mm f/2.8G AF-S ED VR II. Seems to sell for almost $2000 and weight 3.4 lbs. Sigma's 70-200mm f/2.8 II and Tamron's 70-200mm f/2.8 clock in at about the same weight, with the Tamron about a half pound lighter, and both seem to cost around $700. More reasonable, though the fact that the Canon 70-200 weighs about half as much makes it more appealing, despite the smaller aperture. Also, I would guess that the Canon L series lens would hold it's value a bit better.