RTS game for the computer.?

command and conquer is ok - EA has ruined the series now so dont get RA3 or CnC4!! waste of money.
if you can wrap your head around economies quite easily then supreme commander:forged alliance is easily the best RTS in the past decade.
starcraft is a classic and is worth playing if you can get it running with win7
total war series is very good but the main gameplay is turn-based until there's a battle.