There are several ways:
1) You have an Acer oem machine with vista, so there may or may not be Windows 7 drivers
available. Look up the acer support page for your model and download the Windows 7 drivers if they are available. Of course this can be done after upgrading too.
2) If only vista drivers are available, you can use those but in addition you can locate generic drivers for well known devices such as Realtek high def audio (thats the sound card you have). Your machine has somewhat older hardware such as the 965 express onboard gfx, I think no drivers were released for this one after 2009, you can look up intel's support page for this.
3) Device drivers are also offered through windows update or just go to the device manager, right click on the device then click update. But windows database drivers may not be updated.
4) If you have the .exe file for the driver
, just double click to install, if its zipped extract to a local folder first then run the setup file.
5) A nifty thing you can do is to backup existing installed drivers using a tool like Double driver. After upgrading to Windows 7, you can restore any of he backed up drivers if no updated driver is available. Will save you some bandwidth if you're on a limited connection.
6) All installed drivers are saved in he location "C:\Windows\System32\DriverStore\FileRepository", so one can also backup this folder, then point the devices in device manager to it.