The simple answer is no, at least not until DOW 2
The forthcoming Soulstorm judging by the demo more than matched the previous 3 games and will take the playable faction count to a whopping 9 races, representing huge value for money and masses of depth that comes in learning the strengthes and weaknesses of said factions.
I have to admit I've only ever played as 5 of the original 7 factions from the original 3 games, I found the one I liked and stuck with it like alot of online players seem to do. Its speaks volumes though that a game that I've had for a very long time and have put in my fair share of hours has so much content that 2 of the in game factions have remained untouched.
This is a no brainer purchase in my eyes, only thing is DOW is so popular that I forsee many already owning at least one DOW title in much the same vein as when they released the Orange Box. That said still a great package and a title which matches up to the other two RTS legends on PC, Company of Heroes and Supreme Commander by providing a more conventional real time strategy experience.