It really depends on a couple of things: First, what version of Vista are you using? Second, how much horsepower do you have. I hae a newer Alienware machine and havce both SQL2005 & SQL2008 running on it. If I were you, I’d go with 2008. If it seems to slow your machihne, you may wanna try SQL2008 Web Edition.
The different editions of the engine as essentially the same. They all have the same footprint on the machine.
I would recommend only running the SQL Server when you actually need it to save resources. I have SQL 2005 and SQL 2008 installed on my laptop, but I keep the services stopped unless I’m actually working with the service.