You may have bought a pre-built/branded computer, but it is built with the same components that those of us that build our own use. There may be a few less features and/or locked bios settings on a pre-build, but at the heart of it they are the same. For a laptop yes you pretty much have to rely on the computer manufacturer, but for a desktop you can go directly to the component manufacturer's site(s).
As for
drivers for yours here is the motherboard that is in it,
Foxconn - Products: Motherboard
which has an AMD chipset (780V +SB700) as well as from your specs you have a HD 4350. You can get the latest
drivers for both directly from AMD,
Downloads
for the audio it has the Realtek ALC662 and you can find links to the latest for it here,
Latest Realtek HD Audio Driver Version
Then again you could also just leave well enough alone if everything is working as expected. Also on a properly working system the only
drivers that should be updated after the initial Windows install are the video and possibly the audio drivers, as they can and do contain fixes usually for new games as they come out. If you're not a gamer or there is nothing in the new
driver that would benefit you, you can leave them alone.