I have a Minolta XG-M which is a very similar camera to the X300 and I love using it. I say stick some film and a battery in it and have a play. Sadly the lenses from the manual Minolta cameras don't fit the Sony DSL bodies without an optical adapter. Shame as the Minolta Rokkor lenses are amongst some of the nicest manual focus lenses I've used and can be had for peanuts these days.
Edited to say....that Tamron lens you have could well be an Adaptall and can be used on lots of cameras.