I think your slow start and shutdown has more to do with the software running at boot time (which also need closing down before shutdown can complete).
Can you post a screen shot of this,
go to the start menu and type msconfig in the run line, press enter a panel will arrive, click the tab for start up and we can see what's going on.
Only update your Bios because you need to take advantage of a hardware fix or OS compatibility, there are other far safer things you can do and I don't believe it will make the slightest difference.
BTW if was designed to run Vista it will be fine with Windows 7.