In my opinion it is a backward step,im sure the problems you have had AL can/could be rectified.
We have 4 Vista machines here,all been updated to sp1 with no problems.
I often test various pieces of software and not to mention the Anti tools availible for specialized use.
These i run with no special preparation (only a new Ati image created) so basically it can be high risk...yet i am yet to have any real problems.
My guess the reason why you are not offered sp1 is hardware related..but this will come in time.
Explorer crashing...i can only assume you have a software conflict somewhere or even corrupt data.
Shame really as i think Vista is a tough cookie,it dosnt break as easily as xp.