Being a huge fan of Chris Taylor and the orignal Total annihilation (yes we forgive you for TA kingdoms, Gnugs rule and I married She-Devil), I'm currently playing Supreme Commander http://www.supremecommander.com/
It had been thought that this would be one of the first games to deliver DirectX 10, and "push the envelope" by using dual core, ridiculously expensive graphic cards and the like. Alas that is not the case now. I expect DirectX 10 will become mainstream in 2008 - with hopefully video cards that dont need a mortgage.
Anyways, the games definately worth a play, Very satisfying stomping someones base into the ground after a hard day at the office.
Im really awaiting Starcraft II (http://eu.starcraft2.com/). This will be a must, Blizzard have gone from strength to strength with the Starcraft and Wacraft series.