i dont use home premium, only ultimate and business.
ultimate is stable, tbh it has not given me any problems since i installed it a few months ago.
the only real problem was driver support - but this has improved over time. Most people wont have very many applications they want to run that are not vista compatible and vista itself is more stable than xp. Plus, you get a 64bit version with more driver suppor than xp64.
The only fripe i have with vista is that I cant get a driver for a mini a7 printer I use. It starts up in about 30 seconds and has never hung on me yet. The annoying thing about it is that it asks you if you want to do something all the time as a security thing.
as you say, you wont get aero with basic - but your not missing anything.
if you can afford it, get ultimate as you do get monthly extras (now) from MS that you dont get with any other version.
you could download a hooky copy, but whats the point in getting a rootkit like that installed?
the oem version costs just over a £100, so if you really want everything legally, get that after using basic for a while.