I'll be honest I have been out of the PC gaming arena for a while every since II started playing on consoles more.   
 
However now thanks to the new PC I have just bought I am back with a vengeance.  The PC edition of Mass Effect 2 and Dawn of War II are my current games of choice but you also cannot go wrong with the latest Tales of Monkey Island and Audiosurf.  
 
However the big reason I am so glad to be back is Steam itself.  Microsoft really need to take some lessons from Valve on this when it comes to Games for Windows Live.  The integration is seamless the community is fantastic and the PC is the only way to play for me at the moment thanks to this. 
 
Feel free to add me on steam (meegs6sic6) or GFWL (DeadSoul2004) I am always looking for people to play with/against