386sx 20Mhz, first game I bought was Aces of the Pacific and saved up for a CH Flightstick just to play.
By gum, it was a baptism of fire getting Aces to work, took me about 2 nights. I was barely getting my head around DOS and had to create a boot disk, load mouse drivers, understand Himem, sound drivers and Emm386 memory!
I will never forget when the intro loaded! Brilliant game and still playable now.
GP Unlimited was my next game, it was an F1 game produced by Accolade of Test Drive fame. With GP Unlimited it had its own circuit builder, where you could make your own tracks just like Scalextric, and race against AI. You could make circuits which were gigantic, honestly, take 20 mins to complete a lap.
The physics were not great, its a shame as the idea was quite clever. The original Microprose F1 GP is a much better game and very nostalgic to play now (a time when F1 was decent).