I have been asked a number of questions about compatibility of old Minolta lenses and Sony dSLRs. It is always surprising to me since I think this compatibility is one the best selling points for the Alpha line.
The answer is yes, in almost all cases. All Minolta auto-focus lenses are compatible without exception. The only places that you might find incompatibility are in the oldest 3rd party lenses. Although they may be Minolta (Sony) A-mount and auto-focus, for some reason they wont AF. I have (or had, can't remember where it is...) a first generation Sigma 28-70 f-something that doesn't work, but honestly this old junky lens isn't even worth trying.
You can buy without fear when it comes to old Minolta lenses. Anything from the original Minolta 50/1.7 to the the Konica-minolta 28-75/2.8 will work fine. The same is almost true of the 3rd party lenses as well - there are only a few very old examples that do not work.