I think the Age of Empires games are easier for RTS novices than something like Starcraft. The pace is a bit slower in AOE. Also, there are newer sci-fi RTS games that might have surpassed Starcraft such as C&C 3, Warhammer, Supreme Commander, Homeworld. They sure as hell will make much better use of your 8800 GTS than Starcraft.
I'm not a big RTS fan myself since for the time that it takes to learn a PC RTS, you can already beat something like a Final Fatansy game. However, even I think that Company of Heroes is super awesome. It's amazing how COH, even with so much going on, can look better than most WW2 shooters. You probably don't like the setting but I think the demo's worth a try.