What kind of problem are you having? I don't remember having problems with it on my desktop at home which has Windows 7, and I just tried it on my uni computer here - with Windows 7 as well - and it started and loaded a colony game fine.
Then again I'm using the version you can download from Outpost Universe, so if you're using an original disc that might be why we get different results.
Same version, I think. It simply doesn't start; the thing goes to whatever settings it decides it wants to run in and then goes back to desktop. I'm not even sure the process appears in the task manager. I'll redownload and try again.
EDIT: It appears I wasn't. Oh well, let's see if this works...
EDIT EDIT: Well that didn't work either; it appears in the task manager at around 1300 K memory used briefly, but the game never appears to actually start.
Command and Conquer 3: Tiberium Wars is great, but I'm completely stuck on the last GDI mission at Ground Zero. I don't want to use the "Big Boom" for story reasons, and I'm reluctant to lower the difficult (I'm playing on normal). Anyone here ever beaten that mission?
Few times. Once resulted in an epic saga of a few Pitbulls and my Ion Cannon uplink being the only thing left, desperately holding off the Scrin warships until I can just push the button one more time...
My primary suggestion is to remember that NOD's harvesting operation is separate from its main base and can be taken out by a relatively small force. Lean left as you head straight up from your base. Get their missile silos if you can (I seem to remember it's possible), and remember to reserve money to replace your Refinery; it will get targeted by them.
You will probably have to blood and iron your way through NOD, but if you've killed their harvesting operations it shouldn't be awful. Play conservative; you have neither the time nor the cash to build gigantic death fleets of Mammoth tanks, and your units are individually valuable. Against the Scrin, establish a holding front; cheap and mobile anti-air like Pitbulls are your friends here. You'll have some time, since they generally don't press you as hard as NOD does or drop missiles on your base, so get your Ion Cannon uplink working and zap 'em good.