I have noticed on this forum that a lot of people are saying that the camera they currently own has a snail like autofocus. I recently purchased a Minolta Dynax 404Si/ Maxuum STsi and soon after I put the deposit down I read reviews that the AF is very slow on that camera. But as soon as I tried it out I didn't see what the fuss was all about. It was perfect for my needs. The AF was faster that I thought it would be and the only time I thought it was slow was when I was using it on still objects at home rather that the fast moving aircraft !
Sorry about all the waffling but my point is we should be glad that AF exists otherwise we'd be losing twice as many shots trying to use MF until we get used to it. Be glad with what you have - unless you have $1500 for a Nikon F5 !
Just thought I'd share my thoughts