You know, I never thought I'd ever see a Castlevania game arrive on Steam, but lo and behold one has.
Castlevania: Lords of Shadow Ultimate Edition is now available for pre-purchase on Steam, and if you pre-order you'll get ten percent off the regular price of $29.99.
Castlevania: Lords of Shadow Ultimate Edition will include the core game as well as the Reverie and Resurrection DLC packs. Outside of the 2.4Ghz Intel Core 2 Duo processor, the minimum specs aren't that bad (though a quad core is recommended).
Fun little trivia note; this is not the first time an official Castlevania game has hit PCs (not counting home computers such as the MSX). Back in 2002 Konami released Konami Collector's Series: Castlevania & Contra for PCs that included all three Castlevania games, Contra, and Super C for the NES. Kind of sad it took this long to get another Castlevania game ported to the PC, but at least it finally happened (unless another one was released that I don't know about).