The country has a total population of 6 million. Almost all of this population lives in fairly large population centers along the coast, with wide stretches of uninhabited desert separating two narrow belts of cultivation, one in the west and one in the east. The primary cities of Libya have populations as follows:

In rebel hands:
Benghazi - 670,000
Areas west of Benghazi - 600,000
TOTAL: 1.27 million

In Qaddhafi hands:
Tripoli - 1 million
Sirte - 140,000
TOTAL: 1.14 million

Unclear:
Misrata - 550,000
Ajdabiya and environs - 170,000
Zawiya - 270,000
TOTAL: 1 million

Zawiya and Ajdabiya are in the unclear category because they rose up against Qaddhafi but there are now Qaddhafi troops there. Misrata is apparently fighting off a Qaddhafi attack.

There are almost certainly enough anti-Qaddhafi forces in Tripoli itself (like Tajura, the area that was out of his control as late as last week) that a rebel push on the capital would certainly see Qaddhafi's power crumble, assuming that his air assets and vehicles are destroyed. At most I would think close air support would be needed, or perhaps, in a few situations, some discreet helicopter-borne operations with a few special forces briefly on the ground and then out again before anyone really knows what happened. It's more like what we did in 2001 in Afghanistan in the beginning.

Either way, the insurgents have enough manpower that their troops supported by our logistics could wipe out what I assume are some very demoralized Qaddhafi troops. It sounds as though only the 30,000 or so special troops under the command of Qaddhafi's son have really done any fighting.