Are classic games released on Steam are somehow optimized for modern computers?

I'm wondering are classic games (released earlier than say 2000) on Steam are somehow optimized to run on modern OSes and/or hardware?

I own one such game, but it's always takes some time to set it up running (installing latest patches, tuning compatibility, etc.) on a new Windows OS. Even with some latest patches it does have some minor graphics artifacts.

This game is currently on sale on Steam, and I think maybe it's worth to pay a little to remove all this annoyances? Does Steam somehow guarantee that this game will run on all modern OSes (I'm using Windows 8 Pro x64 now), have all latest patches installed and maybe even have some tweaks or unreleased patches to run it better?

Or still having original CD + patches + etc. will eventually give me same result?