Not to rain on your parade, but by the time they released windows-only games, Win98 was standard lol. Everything released prior was DOS-based anyway, as well as most of the stuff released during Win98.
However, I'm always excited when a DX10 game comes along...they always (at least, MOST of the time) look gorgeous...Lost Planet, AoC (before they took it out), Hellgate: London, to name a few. DX10 is the new kid on the block, and will only get better with time, and as more games come out, things will be more streamlined.
As I said, I can't get this game to run smoothly at all...I'm using Vista, my DX10.1 is up to date, I have two 8800GTX 756MB cards in SLI...the list goes on, and the game is so choppy, the mouse is so laggy, it's just not worth playing. Thankfully, my father bought this, not me, so I didn't waste the money