Thanks for the comment.
The biggest problem in buying lenses is working out what you want and need. Nothing wrong with the Canon 300mm F2.8 IS, which is a cracking lens and ideal for wildlife photos, but it weighs 2.5kg and together with the 7D at 820gm would weight 3.5kg, which is a bit heavy as a carry round lens. The 70-200mm F2.8 IS together with the 7D would save you 1kg in weight.
I have a Nikon 400mm F2.8 AIS which weighs 6kg, and although a cracking lens doesn't get used as often as it should, because of the weight.