you can upgrade from Vista to Win7, but personally I'd do a clean install,
1. I upgraded my laptop and it took 6 hours
2. clean install took 20 min
3. download the drivers you need for the net card and put them on a USB stick in case there is a problem
4. I would think that if it came with Vista preistalled htere will not be a driver issue, but be prepared
I Would be inclined to add another gig of ram before you upgrade. The acer 5315 is low on ram from the get go.You get what you pay for. But they are good value.
Also they're proned for over heating because the cpu is always backlog with data causing over heating the extra ram help's bigtime. Also check the cooling system while you do the ram they can become full of dust etc. in a very short time. I have two of these laptop's one has had a problem over heating not good.
Mostly caused buy dust and working to hard pushing data. Works mint now no more problems. Transcoding on the fly work's mint even HD Movie's.
After installing windows seven from a complete install its even better. It's just faster at stack dumping (Clearing Ram). I'm still a big fan of Xp Pro just because it's not that demanding and has network tools that you don't get with vista and windows seven unless your willing to be shafted by Bill Gates and pay him at the same time for it. Im sure he doesn't ned the extra cash.
Since you are moving from Vista to Windows 7 you can purchase the upgrade version of Windows 7 and then choose to do an upgrade (where your programs, files, and settings transfer over to Windows 7) or you can choose to do a custom installation where your computer is wiped clean and you start fresh. If you choose to do a custom installation you can still use the upgrade disk, but be sure to back up your programs, files, and settings as they will be wiped during the custom installation.
Here are guides that will help walk you through the process: