OEM Software is legit. It is the same as any other operating system or such you can buy, the only difference is that they are supposed to be sold with a purchase of a new computer, kind of like a discount if you will. I bought a copy...
I use a soft cloth to get rid of the dust build up, you can buy them at wal-mart as they are sunglasses cleaning lense cloths....very soft. Other than that for smudges and such i would recomend something that you can buy so you don't...
I use the standard drivers that came with the system. They are out of date i assure you however i score well on 3dmark and my games play well. So i don't have the need for Omega drivers ( with the overclocker radlinker ), that is...