Im not Critisizing W 7 but just dont see the take up being as fast as MS say and with MS now deciding not to have a ie less version for europe it may all change price wise in the upward direction at first.
But i belive within a year (when most people will bother looking at once afters have tested) due to competion (google and apple are about to be battered in the US and the EU will soon follow no doubt as big fines can be imposed) that we will have very very cheap os avaiable which will be enough for the majority of occasional users.
I can say from our testing yes it does seem to run far better than Vista and often XP, it also improves performance on low spec devices but that being a plus point depends on the cost of a unit to the company (lease or purchased) compared to the cost of an entire os,drivers and applications.
If you are buying a pc then make sure you get a free upgrade to windows seven included if at all possible or wait if the choice is Vista.
But if your pc running ok and what not, dont rush out unless you can spare the cash would be my advice.