Primes are good
They are sharp, but bear in mind they are not zooms, so only good for particular jobs - I will use a prime usually for sport (cricket, football(soccer) etc..) - of course a decent prime is expensive - my 400mm F2.8 cost around £6,000 ($12,000 on current version rates)!!!
If you have any photography questions just ask. I am a canon man myself with the following kit...
1DMK11
1DMk11N
400mm F2.8
300mm F2.8
100-400mm
70-200mm F2.8
16-35 f2.8
15mm Fisheye
1.4x converter
2x converter
various filters, flashunits etc... (and the odd item, I have forgotten)
Another good site is
http://www.photography-on-the.net
at the moment - but expanding all the time....) 
